System for and method of controlling shifting in gear position in
Contents
1. 45 Date of Patent OTHER PUBLICATIONS Service Manual Nissan Full Range Electronically Controlled Automatic Transmission of RE4RO1A Type 1987 A261C07 issued by Nissan Motor Com pany Limited in Mar 1987 Japanese Service Manual for Automatic Transmission Types L4N71B and E4N71B Nissan Motor Company Limited Nov 1982 Primary Examiner Dwight Diehl Attorney Agent or Firm Foley amp Lardner 57 ABSTRACT An automatic transmission with a downshift control is disclosed Upon deceleration the downshift is effected to cause engine brake running with downshifted state to take place When the driver depresses an accelertator pedal to open the engine throttle i e a power demand the engine brake running with downshifted state is to be released but with a predetermined delay time More specifically the engine brake running with downshifted state is released upon expiration of the predetermined delay time after the power demand has been detected In the second embodiment the release timing is more precisely controlled such that the delayed release be comes moot when the power demand disappears so that the downshifted state is immediately released when the accelerator pedal is released after it has been de pressed 10 Claims 6 Drawing Sheets iS ENGINE SHIFT SHIFT CONTROLLING DEMANDED DELAY SETTING AUTOMATIC TRANSMISSION Sheet 1 of 6 5 022 286 June 11 1991 U S Patent NO2. power demand is detected when a throttle is opened 6 A method as claimed in claim 5 wherein the open ing of said throttle is detected when an idle switch is rendered OFF 7 A system for controlling shifting in gear position in an automatic transmission for an automotive vehicle when the vehicle is subjected to deceleration wherein the automatic transmission is downshifted and condi tioned in engine brake running state after predetermined conditions have been met the predetermined conditions including absence of a power demand by a driver of the automotive vehicle the system comprising means for detecting the power demand and control means for determining whether or not the power demand is detected after the predetermined conditions have been met and then releasing the automatic transmission from the engine brake run ning state upon expiration of a predetermined delay time beginning with the detection of the power demand after the predetermined conditions have been met l 8 A system for controlling shifting in gear position in an automatic transmission for an automotive vehicle 50 60 65 when the vehicle is subjected to deceleration wherein the automatic transmission is downshifted and condi tioned in engine brake running state after predetermined conditions have been met the system comprising means for detecting the power demand and control means for determining whether or not the power demand is detected aft
3. degree i e ACSACsz7 where ACser is a predetermined negative value Describing along the flow chart shown in FIG 3 at a step 40 it is determined whether the D range position is selected or not When the D range position is not selected at the step 40 the program proceeds to a step 42 where the flag FDS is set equal to 0 zero before the program comes to an end When at the step 40 it is determined that D range position is selected the pro gram proceeds to a step 44 where it is determined whether an idle flag FIDL is set equal to 1 or not When it is determined that the flag FIDL is set equal to 0 the program proceeds to the above mentioned step 42 be fore the program comes to an end When it is deter mined that the flag FIDL is set equal to 1 the program proceeds to a step 46 where it is determined whether the flag FDS is set equal to 1 or 0 When it is determined that the flag FDS is set equal to 1 the program comes to an end When it is determined at the step 46 that the flag FDS is set equal to 0 the program proceeds to a step 48 where it is determined whether the brake switch is rendered ON or OFF When it is determined that the brake switch is rendered OFF the program comes to an end When it is determined at the step 48 that the brake 5 022 286 5 switch is rendered ON the program proceeds to a step 50 At the step 50 predetermined data corresponding to a gear position which the automatic transmission is shifted to ar
4. the idle flag FIDL is equal to 1 the program proceeds to a step 80 where it is determined whether the content of the timer T is equal to 0 zero or not When it is determined that the content of the timer T is not yet reduced down to 0 the program comes to an end with out clearing the idle flag FIDL When it is determined at the step 80 that the content of the timer T is equal to 0 the program proceeds to a step 82 where the idle flag FIDL is cleared and set equal to 0 The decrement of the reduction timer T is performed along with a pro _ 5 25 45 50 60 65 6 gram as illustrated by the flow chart shown in FIG 6 which is exected upon expiration of a predetermined period of time In FIG 6 at a step 84 it is determined whether the content of the timer T is equal to 0 zero or not When it is determined that the content of the timer is not equal to 0 the program proceeds to a step 86 where the content of timer T is decreased by one From the preceding description of the first embodi ment it will now be appreciated that the idle flag FIDL is kept equal to 1 until the predetermined delay time Tp is expired after the idle switch has been turned to OFF position Thus the flag FDS is kept equal to 1 until _expiration of the predetermined delay time even after the accelerator pedal has been depressued during the engine brake running with the downshifted state and the program comes to an end after proceeding along
5. with determination of the presence of the power demand by said deter mining step 2 A method as claimed in claim 1 wherein said power demand is detected when a throttle is opened 3 A method as claimed in claim 2 wherein the open ing of said throttle is detected when an idle switch is rendered OFF _ 0 45 8 4 A method of controlling shifting in gear position in an automatic transmission for an automotive vehicle when the vehicle is subjected to deceleration wherein the automatic transmission is downshifted and condi tioned in engine brake running state after predetermined conditions have been met the predetermined conditions including absence of a power demand by a driver of the automotive vehicle the method comprising the steps of determining whether or not there is a presence of said power demand after the predetermined conditions have been met l releasing the automatic transmission from the engine brake running state upon expiration of a predeter mined delay time beginning with determination of the presence of the power demand by said deter mining step as long as the presence of said power demand is kept determined during said predeter mined time delay and releasing the automatic transmission from the engine brake running state upon determination of the ab sence of the power demand by said determining step before expiration of said predetermined time delay 5 A method as claimed in claim 4 wherein said
6. 4 98 and 100 Thus the flag FIDL1 is indic ative of the state of the flag FIDL in the previous cycle or run of the program Thus it will be appreciated that the flag FDS is set equal to 0 when the idle switch is rendered ON again after the idle switch has been ren dered OFF At the step 104 it is determined whether the brake switch is ON or OFF When it is determined that the brake switch is rendered OFF the program comes to an end When it is determined at the step 104 that the brake switch is rendered ON the program proceeds to a step 106 At the step 106 predetermined data corresponding to a gear position which the auto matic transmission is shifted to are obtained by reading operation The predetermined data are the upper limit vehicle speed VH the lower limit vehicle speed VL and the predetermined deceleration ACser Then the program proceeds to a step 108 where it is determined whether the vehicle speed VSP falls in a range which is greater than the lower limit vehicle speed VL but less than the upper limit vehicle speed VH or not When it is determined that the vehicle speed VSP does not fall in the predetermined range the program comes to an end When it is determined at the step 108 that the vehicle speed VSP falls in the predetermined range the pro gram proceeds to a step 110 where it is determined whether the deceleration AC delta C is less than or equal to the predetermined deceleration ACser or not When it is determ
7. 90 it is determined that D range position is selected the program proceeds to a step 94 where it is deter mined whether the flag FIDL is set equal to 1 or not When at the step 94 it is determined that the flag FIDL is set equal to 0 the program proceeds to a step 96 where a flag FIDL1 is set equal to 0 and then to the above mentioned step 92 where the flag FDS is set equal to 0 When at the step 94 it is determined that the flag FDL is set equal to 1 the program proceeds to a step 98 where it is determined whether the flag FIDL1 is set equal to 1 or not When at the step 98 it is deter mined that the flag FIDL1 is set equal to 1 the program proceeds to a step 102 where it is determined whether the flag FDS is set equal to 1 or 0 When at the step 102 it is determined that the flag FDS is set equal to 1 the program comes to an end When at the step 102 it is determined that the flag FDS is set equal to 0 the pro gram proceeds to a step 104 When at the step 98 it is determined that flag FIDL1 is set equal to 0 the pro gram proceeds to a step 100 where the flag FIDL1 is set equal to 1 and the flag FDS is set equal to 0 and then to the step 104 From the preceding description of the flow chart it will now be noted that the flag FIDL1 is set 5 022 286 7 equal to 0 immediately after the flag FIDL has been set equal to 0 see steps 94 and 96 while it is set equal to 1 immediately after the flag FIDL has been set equal to 1 see steps 9
8. AL NIS SAN FULL RANGE ELECTRONICALLY CON TROLLED AUTOMATIC TRANSMISSION OF RE4RO1A TYPE 1987 A261 07 issued by Nissan Motor Company Limited on March in 1987 This auto matic transmission is disclosed in U S Pat No 4 680 992 issued to Hayasaki et al on July 21 1987 which is hereby incorporated by references in this ap plication in its entirety FIG 1 is a functional block diagram of a first em bodiment of a system for controlling shifting in gear position in an automatic transmission A vehicle speed detecting block 10 counts the occurrences of a pulse generated by a vehicle speed sensor for a predetermined period of time for example 100 ms or 354 ms and generates the result as a vehicle speed indicative signal The vehicle speed sensor is provided on an output shaft of an automatic transmission 24 A brake operation detecting block 12 is provided where a brake signal generated by a brake switch is detected and it is deter mined whether the brake is operated or not A decelera tion detecting block 14 is provided where a derivative of the vehicle speed indicative signal from the vehicle speed detecting block 10 during a predetermined period of time is calculated and the result is outputted as a deceleration indicative signal Alternatively the decel eration which the vehicle is subject to can be directly given by a deceleration sensor mounted to measure the longitudinal deceleration which the vehicle is subject to An id
9. E4N71B type is known This automatic transmission is manufactured by Nissan Motor Company Limited in Japan and described in a publication NISSAN AUTOMATIC TRANS MISSION L4N71B TYPE E4N71B TYPE SER VICE MANUAL 1982 A261C04 issued by Nissan Motor Company Limited on November in 1982 This known transmission comprises a downshift solenoid a shift switch an idle switch a vehicle speed sensor a brake switch and a control unit As described on page 12 of the above mentioned publication the downshift solenoid is rendered ON when the shift switch indicates that the third gear position is established in D range the vehicle speed sensor detects a vehicle speed falling in a predetermined range from 30 km h to 50 km h the brake switch is rendered ON and the idle contacts of the throttle switch are rendered ON According to this downshift control the downshift solenoid is rendered OFF to cause an upshift to take place in the automatic transmission when the idle switch is rendered OFF in response to the driver s depressing of an accelerator pedal This abrupt upshift from the downshifted state induces a shock and an unplesant ride feel or sensation to the driver An object of the present invention therefore is to provide a system for and a method of controlling the gear position in an automatic transmission when an automotive vehicle which the automatic transmission is mounted on is subject to deceleration which are im proved such
10. ILVWHOANI dO SGNIM YJHLO 8 NOISSINSNVHL bE JLLVANOLNY NIL9313Q ONILLIS AV13QA 3LV1S 370i 92 9I GaaqNnvwaa ONITIOULNOD LAHS 9NI193130 NI19313A 14IHS NMOG 3yvua NOILVHa 13930 GaadS 31OIH3A JNI NI SI co ONILOALSG NOILVH3S3d0 ZI JyJvVHYg B Sia U S Patent June 11 1991 FIG 2a START RETURN Sheet 2 of 6 5 022 286 RETURN U S Patent June 11 1991 Sheet 3 of 6 5 022 286 RETURN U S Patent June 11 1991 Sheet 4 of 6 5 022 286 FIG 4 START READ OPERATING CONDITION TABLE LOOK UP SHIFT PATTERN j DATA T DETERMINE GEAR POSITION GP SUBPROGRAM FOR SHIFTING PROCEDURE SUBPROGRAM FOR SHIFTING PROCEDURE ENGAGE OVERRUNNING CLUTCH RETURN U S Patent June 11 1991 Sheet 5 of 6 5 022 286 FIG 5 START RETURN RETURN U S Patent June 11 1991 Sheet 6 of 6 5 022 286 FIG 7 RETURN 5 022 286 1 SYSTEM FOR AND METHOD OF CONTROLLING SHIFTING IN GEAR POSITION IN AUTOMATIC TRANSMISSION BACKGROUND OF THE INVENTION The present invention relates to a system for and a method of controlling shifting in gear position in an automatic transmission and more particularly to a sys tem for and a method of controlling shifting in gear position in an automatic transmission when an automo tive vehicle which the automatic transmission is mounted on is subject to deceleration An automatic transmission of the
11. United States Patent 19 Takizawa 54 SYSTEM FOR AND METHOD OF CONTROLLING SHIFTING IN GEAR POSITION IN AUTOMATIC TRANSMISSION 75 Inventor Satoshi Takizawa Yokosuka Japan 73 Assignee Nissan Motor Co Ltd Yokohama Japan 21 Appl No 336 431 22 Filed Apr 11 1989 30 Foreign Application Priority Data Apr 11 1988 JP Japan oo esseecseeserenerenenees 63 87390 Apr 11 1988 JP Japan cacccessosssssescsessessesssses 63 87391 5U Int CUS scsstsiscitcceseestcscesszeopenseseseageaseaee B60K 41 06 52 Se O E E AET 74 866 58 Field of Search 74 866 867 865 877 364 424 1 56 References Cited U S PATENT DOCUMENTS 4 041 809 8 1977 Dick et al nsesssesssressserererre 74 866 4 253 346 3 1981 K hnle oc eseseseeeeeeeseeee 74 866 4 412 290 10 1983 Pannier scsscessssesreeeseereres 74 866 4 456 107 6 1984 Ito etal on sseseeeesererereneneees 74 866 4 457 410 7 1984 Suga et al 74 866 4 463 822 8 1984 Tanigawa et al 74 866 4 551 802 11 1985 Smyth oc ccssseseserseneeereeenee 74 866 4 671 139 6 1987 Downs et al 4 680 992 7 1987 Hayasaki et al G 4 730 519 3 1988 Nakamura et al oo 74 866 4 823 646 4 1989 Yoshimura et al 74 866 BRAKE OPERATION DETECTING DETECTING DETECTING IDLE STATE DETECTING OTHER KINDS OF INFORMATION VEHICLE SPEED aan DECELERATION ma BRAKE DOWN 5 022 286 Jun 11 1991 u1 Patent Number
12. d power demand disappears releasing the automatic transmission from the engine brake running with downshifted state immediately after said power demand has disappeared According to another aspect of the present invention there is provided a system for controlling shifting in gear position in an automatic transmission for an auto motive vehicle when the vehicle is subjected to deceler ation wherein an engine brake running with down shifted state is initiated when predetermined conditions are met the system comprising means for detecting a power demand by a driver of the automotive vehicle and means for releasing the automatic transmission from said engine brake running with downshifted state upon expiration of a predetermined delay time after said power demand has been detected According to still further aspect of the invention there is provided a system for controlling shifting in gear position in an automatic transmission for an auto motive vehicle when the vehicle is subjected to deceler ation wherein an engine brake running with down shifted state is initiated when predetermined conditions are met the system comprising means for detecting a power demand by a driver of the automotive vehicle and means for releasing the automatic transmission from said engine brake running with downshifted state upon expiration of a predetermined delay time after said power demand has been detected unless said power demand disapp
13. e obtained by reading operation The prede termined data are the upper limit vehicle speed VH the lower limit vehicle speed VL and the predetermined deceleration ACsgr Then the program proceeds to a step 52 where it is determined whether the vehicle speed VSP falls in a range which is greater than the lower limit vehicle speed VL but less than the upper limit vehicle speed VH or not When it is determined that the vehicle speed VSP does not fall in the predeter mined range the program comes to an end When it is determined at the step 52 that the vehicle speed VSP falls in the predetermined range the program proceeds to a step 54 where it is determined whether the absolute value of the deceleration AC delta C is greater than or equal to the absolute value of the predetermined decel eration ACsgr or not When it is determined that the absolute value of the deceleration AC is less than the absolute value of the predetermined deceleration ACszr the program comes to an end When it is deter mined at the step 54 that the absolute value of the decel eration AC is greater than or equal to the absolute value of the predetermined deceleration ACser the program proceeds to a step 56 where the flag FDS is set equal to 1 Referring to FIG 4 the shift controlling block 22 is further described At a step 60 the operating conditions of the vehicle are obtained by a reading operation Then the program proceeds to a step 62 where a table lo
14. ears said releasing means being opera tive to release the automatic transmission from the en gine brake running with downshifted state immediately after said power demand has disappeared BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is a functional block diagram of a first embodi ment according to the present invention FIG 2a is a flow chart of a program for counting a pulse generated by a vehicle speed sensor FIG 2b is a flow chart of a program for determining a deceleration to which an automotive vehicle is sub jected FIG 3 is a flow chart of a program for controlling a downshift flag FIG 4 is a flow chart of a program for effecting downshift and engine brake running FIG 5 is a flow chart of a program for controlling a idle flag such that the idle flag is kept being set equal to 1 for a predetermined delay time after an idle switch has been rendered OFF FIG 6 is a flow chart of a program for decrement of a timer and FIG 7 is a similar view to FIG 3 illustrating a flow chart of a program used in a second embodiment ac cording to the present invention DETAILED DESCRIPTION OF THE INVENTION Before describing the embodiments according to the present invention an automatic transmission a which the present invention is embodied or applied to is briefly described This automatic transmission is manufactured 5 022 286 3 by Nissan Motor Company Limited in Japan and de scribed in a publication SERVICE MANU
15. er the predetermined conditions have been met and then releasing the automatic transmission form the engine brake run ning state upon expiration of a predetermined delay time beginning with the detection of the power demand as long as the presence of the power de mand is kept determined during said predetermined time delay said the control means being operative to release the automatic transmission from the en gine brake running state upon determination of the absence of the power demand before expiration of said predetermined time delay 9 A method of controlling shifting in gear position in an automatic transmission for an automotive vehicle the method comprising the steps of 5 022 286 9 determining one gear position determining whether predetermined conditions are met or not said predetermined conditions includ ing absence of a power demand by a driver of the automotive vehicle conditioning the automatic transmission at another gear position lower than said one gear position and in engine brake running state after it has been deter mined that said predetermined conditions are met detecting the presence of said power demand and conditioning the automatic transmission at said one gear position and releasing the automatic transmis sion from said engine brake running state upon expiration of a predetermined delay time beginning with detection of presence of said power demand after it has been determined that said predetem
16. gnal from the block 20 indicative of the fact that the predetermined conditions for effecting down shifting for engine brake running are met the shift con trolling block 22 commands downshifting and engaging of a clutch for effecting engine brake running such as an overrunning clutch in the case of the automatic transmission disclosed in U S Pat No 4 680 992 issued to Hayasaki et al on July 21 1987 which has been hereby incorporated in its entirety by reference 10 5 _ 30 40 45 50 55 60 65 4 The previously mentioned block 26 for setting the delay gives the predetermined delay to the block 20 only when the output of the idle operation detecting block 16 indicates that the idle switch is rendered OFF Referring to FIGS 2a and 2b the deceleration de tecting block 14 is further described This block has a counter C which counts occurences of pulse signals from the vehicle speed sensor The execution of a pro gram as shown by the flow chart in FIG 2a is initiated by interruption occurring in synchronism with the oc currence of pulse signal from the vehicle speed sensor Ata step 30 the content of the counter C is increased by one The execution of a program as illustrated in a flow chart in FIG 26 is initiated upon expiration of a prede termined period of time for example 100 ms or 354 ms At a step 32 a difference AC delta C is calculated by subtracting C from C where C represents the p
17. ined conditions are met 10 A method of controlling shifting in gear position in an automatic transmission for an automotive vehicle the method comprising the steps of determining one gear position 5 20 25 30 35 45 50 55 65 10 determining whether predetermined conditions are met or not said predetermined conditions includ ing the absence of a power demand by a driver of the automotive vehicle detecting the presence of said power demand conditioning the automatic transmission at another gear position lower than said one gear position and in engine brake running state when it is determined that said predetermined conditions are met conditioning the automatic transmission at said one gear position and releasing the automatic transmis sion from said engine brake running state upon expiration of a predetermined delay time beginning with detection of the presence of said power de mand as long as the presence of said power demand remains detected during said predetermined delay time and conditioning the automatic transmission at said one gear position and releasing the automatic transmis sion from said engine brake running state upon absence of said power demand before expiration of said predetermined delay time
18. ined that the absoulte value of the deceleration AC is less than the absolute value of the predetermined deceleration ACsg7 the program comes to an end When it is determined at the step 110 that the absolute value of the deceleration AC is greater than or equal to the absolute value of the predetermined decel eration ACsgr the program proceeds to a step 112 where the flag FDS is set equal to 1 From the above description of the second embodi ment it will be noted that during the period when the release of the engine brake running with the down shifted state is delayed this brake running with down shifted state is released and an upshift takes place imme diately when the accelerator pedal is released again after it has been depressed What is claimed is 1 A method of controlling shifting in gear position in an automatic transmission for an automotive vehicle when the vehicle is subjected to deceleration wherein the automatic transmission is downshifted and condi tioned in engine brake running state after predetermined conditions have been met the predetermined conditions including absence of a power demand by a driver of the automotive vehicle the method comprising the steps of determining whether or not there is a presence of the power demand after the predetermined conditions have been met and releasing the automatic transmission from the engine brake running state upon expiration of a predeter mined delay time beginning
19. le state detecting block 16 is provided where an output signal of an idle switch is detected and it is deter mined whether the engine throttle valve is at the idle speed position or not The idle switch is arranged within the engine throttle chamber A block 18 is provided where the other kinds of information such as a throttle opening degree and an oil temperature of oil used in the automatic transmission which are necessary for the shifting control are detected and generated as output signals There is provided a block 20 for determining whether there is any demand for engine brake downshift Fed to this block 20 are the vehicle speed indicative signal from the block 10 the brake operation indicative signal from the block 12 the idle operation indicative signal from a block 26 accompanied by a delay and the gear position indicative signal from a shift controlling block 22 At the block 20 it is determined whether predeter mined conditions are met for effecting downshifting for an engine brake running or not The output of the block 20 indicative of the result is fed to the shift controlling block 22 The shift controlling block 22 controls shifting in gear position in the automatic transmission 24 in a con ventional manner in the absence of the output signal from the block 20 indicative of the fact that the prede termined conditions for effecting downshifting for en gine brake running are met However upon receipt of the output si
20. ok up operation of shift pattern data is performed based on the operating conditions stored at the preced ing step 60 to determine a gear position GP which the automatic transmission should take The program pro ceeds to a step 64 where it is determined whether the flag FDS is equal to 1 or not When it is determined that the flag FDS is equal to 0 the program proceeds to a step 66 where a subprogram for shifting procedure is executed When it is determined that the flag FDS is equal to 1 the program proceeds to a step 68 where the gear position GP is decreased by 1 Then the program proceeds to a step 70 where the subprogram for shifting procedure is executed Then the program proceeds to a step 72 where the engine brake running clutch i e the overrunning clutch is engaged Referring to FIG 5 the delay setting block 26 is further described At a step 74 it is determiend whether the idle switch is rendered ON or not When it is deter mined that the idle switch is rendered ON and thus the engine throttle is at the idle speed position the program proceeds to a step 76 where the idle flag FIDL is set equal to 1 and a timer is set equal to a predetermined delay time Tp When it is determined at the step 74 that the idle switch is rendered OFF and thus the engine throttle is not at the idle speed position the program proceeds to a step 78 where it is determined whether the idle flag FIDL is equal to 1 or not When it is deter mined that
21. resent content of the counter while C the previous content of the counter given the predetermined period of time ago At a step 34 C is updated and set equal to C Then at a step 36 C is cleared and set equal to 0 zero The difference AC delta C is negative when the vehicle is subject to deceleration and thus variable with the decel eration which the vehicle is subject to and thus used as the deceleration indicative signal Of course the decel eration indicative signal may directly be given by the vehicle mount deceleration sensor or an accelerenome ter Referring to FIG 3 the block 20 for effecting down shifting for engine brake running is further described A flag FDS is provided which is set equal to 1 when the predetermined conditions for effecting downshifting for engine brake running are met This flag FDS is called an engine brake downshift demand flag The flag FDS is set equal to 0 zero when the selector of a manual valve is placed at D range position or an idle flag FIDL which is later described is equal to 0 zero or the brake switch is rendered OFF The flag FDS is set equal to 1 when the selector is placed at the D range position and the idle flag FIDL is equal to 1 and the brake switch is rendered ON and the vehicle speed VSP falls in a range greater than a lower limit vehicle speed VL but less than an upper limit vehicle speed VH and the deceleration AC delta C is less than or equal to a predetermined
22. that the above mentioned shock nor the neither unplesant ride feel encountered in the prior art are eliminated or alleviated SUMMARY OF THE INVENTION According to one aspect of the present invention there is provided a method of controlling shifting in gear position in an automatic transmission for an auto motive vehicle when the vehicle is subjected to deceler ation wherein an engine brake running with down shifted state is initiated when predetermined conditions are met the method comprising the steps of detecting a power demand by a driver of the automo tive vehicle releasing the automatic transmission from said engine brake running with downshifted state upon expiration of a predetermined delay time after said power demand has been detected According to a further aspect of the present inven tion there is provided a method of controlling shifting in gear position in an automatic transmission for an automotive vehicle when the vehicle is subjected to deceleration wherein an engine brake running with downshifted state is initiated when predetermined con ditions are met the method comprising the steps of ma 5 N 0 30 40 45 50 55 60 65 2 detecting a power demand by a driver of the automo tive vehicle releasing the automatic transmission from said engine brake running with downshifted state upon expiration of a predetermined delay time after said power demand has been detected unless sai
23. the steps 40 44 and 46 upon execution of each cycle until expiration of this delay time As a result the automatic transmission is prevented from upshifting immediately after the accelerator pedal has been depressed during the engine brake running with the downshifted state alleviating shock or unplesant ride feel given to the driver A second embodiment according to the present in vention is described This embodiment is substantially the same as the first embodiment except the manner of setting an engine brake downshift demand flag FDS at a block 20 According to this second embodiment the flag FDS is set equal to 0 when the selector of a manual valve is not placed at D range position or FIDL 0 or the brake switch is rendered OFF or FIDL 1 and FIDL1 0 The flag FDS is set equal to 1 when the selector is placed at the D range position and FIDL 1 and the brake switch is rendered ON and the vehicle speed VSP falls in a range greater than a lower limit vehicle speed VL but less than an upper limit vehicle speed VH and the deceleration AC is less than or equal to a predetermined deceleration ACseEr7 Describing further along the flow chart shown in FIG 7 at a step 90 it is determined whether the D range position is selected or not When the D range position is not selected at the step 40 the program pro ceeds to a step 92 where the flag FDS is set equal to 0 zero before the program comes to an end When at the step
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