EP0045962A2 — Control system for automatic transmission for aut…

Claim 1

Independent Claim 274 words

A control system for an automatic transmission for an automotive vehicle having an engine, an accelerator pedal and a brake pedal, the automatic transmission being adapted for shifting between different gear ratios including a highest gear ratio according to a shift pattern, and including an output member drivingly connected with at least one traction wheel of the automotive vehicle and a torque converter including a pump drivingly connected with the engine, the engine having fuel cut signal generating means for generating a fuel cut signal as long as the engine speed is higher than a predetermined engine speed after the accelerator pedal has been released to cause the automotive vehicle to begin a coasting operation and fuel cut means responsive to the fuel cut signal for suspending the supply of fuel to the engine, said control system comprising: brake pedal position detector means responsive to the brake pedal for generating a brake signal when the brake pedal is depressed; and circuit means responsive to said brake signal for generating a downshift command signal upon depressing the brake pedal when the fuel cut means suspends the supply of fuel to the engine; downshift means responsive to said downshift command signal for changing the automatic transmission from the highest gear ratio down to the next lower adjacent gear ratio, whereby the automatic transmission shifts from the highest gear ratio down to the adjacent lower gear ratio to increase the engine speed, resulting in an increase in the time period when the engine speed remain above the predetermined engine speed to enhance the time period of the operation of the fuel cut means thereby improving fuel economy.

Claim 2

Dependent Claim 274 words

A control system for an automatic transmission for an automotive vehicle having an engine, an accelerator pedal and a brake pedal, the automatic transmission being adapted for shifting between different gear ratios including a highest gear ratio according to a shift pattern, and including an output member drivingly connected with at least one traction wheel of the automotive vehicle and a torque converter including a pump drivingly connected with the engine, the engine having fuel cut signal generating means for generating a fuel cut signal as long as the engine speed is higher than a predetermined engine speed after the accelerator pedal has been released to cause the automotive vehicle to begin a coasting operation and fuel cut means responsive to the fuel cut signal for suspending the supply of fuel to the engine, said control system comprising: brake pedal position detector means responsive to the brake pedal for generating a brake signal when the brake pedal is depressed; and circuit means responsive to said brake signal for generating a downshift command signal upon depressing the brake pedal when the fuel cut means suspends the supply of fuel to the engine; downshift means responsive to said downshift command signal for changing the automatic transmission from the highest gear ratio down to the next lower adjacent gear ratio, whereby the automatic transmission shifts from the highest gear ratio down to the adjacent lower gear ratio to increase the engine speed, resulting in an increase in the time period when the engine speed remain above the predetermined engine speed to enhance the time period of the operation of the fuel cut means thereby improving fuel economy.

Claim 3

Dependent Claim 37 words

A control system as claimed in claim 1, further including a micro processor responsive at least to a coasting operating condition, said engine speed, said micro processor generating said fuel cut signal and said downshift command signal.

Claim 4

Dependent Claim 145 words

A control system as claimed in claim 1, further comprising: gear ratio generating means responsive to the automatic transmission for generating 'a highest gear ratio signal when the automatic transmission selects the highest gear ratio; accelerator pedal position detector means responsive to the accelerator pedal for generating an idle signal when the accelerator pedal is released; engine speed related value generating means for generating an engine speed related value which varies as a function of the engine speed and the gear ratio selected by the automatic transmission; comparator means for comparing said engine speed related value with a predetermined engine speed related reference value and for generating a range signal when said engine speed related value is higher than said engine speed related reference value, wherein said circuit means is further responsive to said idle signal, said range signal and said highest gear ratio signal.

Claim 5

Dependent Claim 39 words

A control system as claimed in claim 3, wherein said engine speed related value is a vehicle speed of the automotive vehicle, said vehicle speed being determined by an engine speed vs., vehicle speed for the highest gear ratio.

Claim 6

Dependent Claim 21 words

A control system as claimed in claim 3, wherein said engine speed related value is an engine speed of the engine.

Claim 7

Dependent Claim 34 words

A control system as claimed in claim 1, wherein said circuit means is responsive to the fuel cut signal to determine that the fuel cut means suspends the supply of fuel to the engine.

Claim 8

Dependent Claim 49 words

A control system as claimed in claim 6, wherein said circuit means includes a flip-flop circuit which is set by said brake signal when said fuel cut signal is present and remains set as long as said fuel cut signal is present even after said brake signal has terminated.

Claim 9

Dependent Claim 149 words

A control system as claimed in claim 6, including: reference engine speed value generating means responsive to engine coolant temperature for generating a reference engine speed value varying in response to said engine coolant temperature; engine speed sensor for generating an engine speed signal representing the engine speed; comparator means for comparing said engine speed signal with said reference engine speed signal and for generating a fuel cut permission signal when said engine speed signal is greater than said reference engine speed value; said fuel cut means generating said fuel cut signal at least in response to said fuel cut permission signal; and a holding circuit means for maintaining said fuel cut permission signal for a predetermined time period independent of the engine speed signal whereby even if said engine speed drops below said reference engine speed for said predetermined time period, said fuel cut permission signal is generated.

Claim 10

Dependent Claim 53 words

A control system as claimed in claim 1, further comprising: means for generating a lock-up command signal when said downshift means has changed the transmission from the highest gear ratio down to the next lower adjacent gear ratio; and lock-up means responsive to said lock-up command signal for locking up the torque converter.

Claim 11

Dependent Claim 31 words

A control system as claimed in claim 9, including: means responsive to said lock-up command signal for causing the fuel cut means to suspend the supply of fuel to the engine.

Claim 12

Dependent Claim 58 words

A control system as claimed in any one of claims 1-9, including: means for generating a downshift prohibiting signal when the vehicle speed is higher than a downshift prohibiting vehicle speed value; and means responsive to said downshift prohibiting signal for preventing the issuance of said downshift command signal as long as said downshift prohibiting signal is present.

Claim 13

Dependent Claim 48 words

A control system as claimed in claim 1, including gear ratio generating means for generating a gear ratio signal when the automatic transmission selects a predetermined gear ratio signal; and fuel cut prohibiting means responsive to said gear ratio signal for preventing operation of said fuel cut means.

Claim 14

Dependent Claim 256 words

A control method for an automatic transmission for an automotive vehcile having an engine, an accelerator pedal and a brake pedal, the automatic transmission being adapted for shifting between different gear ratios including a highest gear ratio according to a shift pattern, and including an output member drivingly connected with at least one traction wheel of the automotive vehicle and a torque converter including a pump drivingly connected with the engine, the engine having fuel cut signal generating means for generating a fuel cut signal as long as the engine speed is higher than a predetermined engine speed after the acclerator pedal has been released to cause the automotive vehicle to begin a coasting operation and fuel cut means responsive to the fuel cut signal for suspending the supply of fuel to the engine, said control method comprising: generating a brake signal responsive to the brake pedal when the brake pedal is depressed; generating a downshift command signal responsive to said brake signal upon depressing the brake pedal when the fuel cut means suspends the supply of fuel to the engine; and changing the automatic transmission from the highest gear ratio down to the next lower adjacent gear ratio, whereby the automatic transmission shifts from the highest gear ratio to the adjacent lower gear ratio to " increase the engine speed, resulting in an increase in ; the time period when the engine speed remains above the predetermined engine speed to enhance the time period of operation of the fuel cut means thereby improving fuel economy.

Claim 15

Dependent Claim 256 words

A control method for an automatic transmission for an automotive vehcile having an engine, an accelerator pedal and a brake pedal, the automatic transmission being adapted for shifting between different gear ratios including a highest gear ratio according to a shift pattern, and including an output member drivingly connected with at least one traction wheel of the automotive vehicle and a torque converter including a pump drivingly connected with the engine, the engine having fuel cut signal generating means for generating a fuel cut signal as long as the engine speed is higher than a predetermined engine speed after the acclerator pedal has been released to cause the automotive vehicle to begin a coasting operation and fuel cut means responsive to the fuel cut signal for suspending the supply of fuel to the engine, said control method comprising: generating a brake signal responsive to the brake pedal when the brake pedal is depressed; generating a downshift command signal responsive to said brake signal upon depressing the brake pedal when the fuel cut means suspends the supply of fuel to the engine; and changing the automatic transmission from the highest gear ratio down to the next lower adjacent gear ratio, whereby the automatic transmission shifts from the highest gear ratio to the adjacent lower gear ratio to " increase the engine speed, resulting in an increase in ; the time period when the engine speed remains above the predetermined engine speed to enhance the time period of operation of the fuel cut means thereby improving fuel economy.

Claim 16

Dependent Claim 103 words

A control method as claimed in claim 13, further comprising: generating a highest gear ratio signal responsive to the automatic transmission when the automatic transmission selects the highest gear ratio; generating an idle signal responsive to the accelerator pedal when the accelerator pedal is released; generating an engine speed related value which varies as a function of the engine speed and the gear ratio selected by the automatic transmission; comparing said engine speed related value with a predetermined engine speed related reference value to generate a raneg signal when said engine speed related value is higher than said engine speed related reference value.

Claim 17

Dependent Claim 127 words

A control method as claimed in claim 13, further comprising: generating responsive to engine coolant temperature a reference engine speed value varying in response to said engine coolant temperature; generating an engine spped signal representing the engine speed; comparing said engine speed signal with said reference engine speed signal to generate a fuel cut permission signal when said engine speed signal is greater than said reference engine speed value; said fuel cut signal being generated at least in response to said fuel cut permission signal; and maintaining said fuel cut permission signal for a predetermined time period independent of the engine speed signal whereby even if said engine speed drops below said reference engine speed for said predetermined time period, said fuel cut permission signal is generated.

Claim 18

Dependent Claim 35 words

A control method as claimed in claim 13, further comprising: generating a lock-up command signal in response to said downshift command signal; and locking up the torque converter in response to said lock-up command signal.

Claim 19

Dependent Claim 55 words

A control system as claimed in any one of claims 13-16, further comprising: • generating a downshift prohibiting signal when the vehicle speed is higher than a downshift prohibiting value; and preventing the issuance of said downshift command signal in response to said donwhift prohibiting signal as long as said downshift prohibiting signal is present.

Claim 20

Dependent Claim 39 words

A control method as claimed in claim 13, further comprising: generating a gear ratio signal when the automatic transmission selects a predetermined gear ratio; and preventing operation of said fuel cut means in response to said gear ratio signal.

Control system for automatic transmission for automotive vehicle

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