Electronic control device for an automatic power transmission

Claim 2

An electronic control system for a planetary gear set type automatic power transmission having a hydraulic power source, a hydraulic circuitry and hydraulically actuable friction elements to provide a required input/output shaft speed ratio, said control system comprising: A. sensing means to sense vehicle speed; B. sensing means to sense a requirement for downshifting from the lowest to the second lowest input/output speed ratio; C. electronic control means responsive to said sensing means to generate a synchronizing time interval signal and to shift the transmission into the highest and overrunning input/output shaft speed ratio for the period of the time interval signal, the time interval signal being longer the higher the vehicle speed is in order to allow the engine speed to be completely synchronized with the transmission speed for smooth downshifting comprising: 1. a capacitor connected to said sensing means to sense a requirement for downshifting, 2. a diode connected to said capacitor, 3. a p-n-p transistor connected to its base to said diode, 4. an n-p-n transistor connected at its base to the collector of said p-n-p transistor and to said sensing means to sense vehicle speed, 5. a first amplifier connected to the collector of said n-p-n transistor, 6. a first solenoid energisable by said first amplifier, 7. a second amplifier connected to said sensing means to sense a requirement for downshifting,

Claim 3

a second solenoid energisable by said second amplifier, and 9. a d.c. power source, the arrangement being such that when said sensing means to sense a requirement for downshifting sense such requirement, the base of said p-n-p transistor receives a voltage from said d.c. power source through a resistor, said capacitor and said diode rendering said p-n-p transistor nonconductive whereby the voltage at its collector is at negative potential for thereby rendering said n-p-n transistor nonconductive to cause energisation of said first solenoid by said first amplifier, and said second amplifier receiving simultaneously the same voltage as the capacitor to energise the second solenoid, whereby the transmission is shifted to the first speed overrunning ratio for the period of a synchronizing time interval signal, the length of which depends on the characteristics of the capacitor and vehicle speed and is longer the greater the vehicle speed is, and after the time interval signal, both transistors being rendered conductive, causing the first solenoid to be de-energised to effect the downshift; and D. sensing means to sense the degree of opening of throttle valve of an engine carburetor, the electronic control system being responsive to said sensing means to sense the degree of opening of a throttle valve and to said sensing means to sense vehicle speed to develop a signal indicating the requirement for the downshifting.

Claim 4

a second solenoid energisable by said second amplifier, and 9. a d.c. power source, the arrangement being such that when said sensing means to sense a requirement for downshifting sense such requirement, the base of said p-n-p transistor receives a voltage from said d.c. power source through a resistor, said capacitor and said diode rendering said p-n-p transistor nonconductive whereby the voltage at its collector is at negative potential for thereby rendering said n-p-n transistor nonconductive to cause energisation of said first solenoid by said first amplifier, and said second amplifier receiving simultaneously the same voltage as the capacitor to energise the second solenoid, whereby the transmission is shifted to the first speed overrunning ratio for the period of a synchronizing time interval signal, the length of which depends on the characteristics of the capacitor and vehicle speed and is longer the greater the vehicle speed is, and after the time interval signal, both transistors being rendered conductive, causing the first solenoid to be de-energised to effect the downshift; and D. sensing means to sense the degree of opening of throttle valve of an engine carburetor, the electronic control system being responsive to said sensing means to sense the degree of opening of a throttle valve and to said sensing means to sense vehicle speed to develop a signal indicating the requirement for the downshifting.

Claim 5

An electronic control system according to claim 1, and further comprising a command circuit connected to the first amplifier and responsive to a first speed ratio signal to cause the first amplifier to energise the first solenoid, the second solenoid being energised by the second amplifier receiving an actuating voltage from the d.c. power source through the resistor, whereby the transmission is set in the first speed overrunning ratio for any length of time.

Claim 6

An electronic control system according to claim 2, wherein the transmission is set in a second speed ratio by the second amplifier receiving the voltage from the d.c. power source through the resistor to energise the second solenoid.

Claim 7

An electronic control system according to claim 3, wherein the transmission is set in a third speed ratio by a third speed ratio signal, which causes both solenoids to be de-energised.

Claim 8

In an electric control system for controlling the gear ratio selecting means of an automatic power transmission of a motor vehicle, the improvement comprising: A. a downshift detector for generating a downshift pulse signal which lasts while a lower gear ratio is to be established in the automatic power transmission; B. a vehicle speed sensor for producing a vehicle speed signal representative of the vehicle speed; C. a differentiator for differentiating said downshift signal to produce a differentiated downshift signal; D. a first level detector connected to the output terminal of said differentiator, for producing a pulse signal which: 1. has an utmost low voltage while the differentiated downshift signal exceeds a predetermined level, and 2. gradually increases in accordance with the exponential decrease of said differentiated downshift signal after said differentiated downshift signal decreases below said predetermined level, the basic level of said pulse signal being shifted in accordance with said vehicle speed signal; E. a second level detector connected to the output terminal of said first level detector for producing a synchronizing time interval signal when the output signal of said first level detector exceeds another predetermined level; and F. means for energising said gear ratio selecting means so as to permit the gear ratio of the automatic power transmission to shift into the highest and overrunning gear ratio for the period of said time interval signal, the time interval signal lasting the longer the higher the vehicle speed is so as to allow the engine speed to be completely synchronized with the transmission speed for smooth shifting.

Claim 9

In an electric control system for controlling the gear ratio selecting means of an automatic power transmission of a motor vehicle, the improvement comprising: A. a downshift detector for generating a downshift pulse signal which lasts while a lower gear ratio is to be established in the automatic power transmission; B. a vehicle speed sensor for producing a vehicle speed signal representative of the vehicle speed; C. a differentiator for differentiating said downshift signal to produce a differentiated downshift signal; D. a first level detector connected to the output terminal of said differentiator, for producing a pulse signal which: 1. has an utmost low voltage while the differentiated downshift signal exceeds a predetermined level, and 2. gradually increases in accordance with the exponential decrease of said differentiated downshift signal after said differentiated downshift signal decreases below said predetermined level, the basic level of said pulse signal being shifted in accordance with said vehicle speed signal; E. a second level detector connected to the output terminal of said first level detector for producing a synchronizing time interval signal when the output signal of said first level detector exceeds another predetermined level; and F. means for energising said gear ratio selecting means so as to permit the gear ratio of the automatic power transmission to shift into the highest and overrunning gear ratio for the period of said time interval signal, the time interval signal lasting the longer the higher the vehicle speed is so as to allow the engine speed to be completely synchronized with the transmission speed for smooth shifting.

Claim 10

An electronic control system according to claim 5, in which said differentiator includes: A. a capacitor having one terminal thereof connected to the output terminal of said downshift detector; B. a first diode having the anode thereof connected to the other terminal of said capacitor; C. a first resistor having one terminal thereof connected to the cathode of said first diode and the other terminal thereof grounded; and D. a series connection of a second diode and a second resistor, which series connection is connected between said other terminal of said capacitor and the ground.

Claim 11

An electronic control system according to claim 6, in which said first level detector includes a first transistor having the base thereof connected to said cathode of said first diode, a third resistor delivering a voltage to the emitter of said first transistor, and a fourth resistor connected between the collector of said first transistor and the output terminal of said vehicle speed sensor.

Claim 12

An electronic control system according to claim 7, in which said second level detector includes a voltage divider for producing a voltage proportional to the potential of the collector of said first transistor, and an amplifier for producing said time interval signal when the voltage from said voltage divider exceeds a predetermined voltage.