Interrelated power delivery controls – including engine control – Transmission control – Transmission controlled by engine
Patent
1995-08-17
1997-07-15
Ta, Khoi Q.
Interrelated power delivery controls, including engine control
Transmission control
Transmission controlled by engine
477146, 477156, F16H 6106
Patent
active
056478194
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a speed change control method for an automatic transmission, and more particularly, to a speed change control method for an automotive automatic transmission, which reduces a shift shock caused by a skip down-shift and shortens a time period required for a speed change.
BACKGROUND ART
An automotive automatic transmission generally includes a transmission mechanism having planetary gears which include speed-changing elements (hereinafter referred to as gears) such as sun gears and planetary carriers, and hydraulic friction engaging elements such as hydraulic wet type multiple disk clutches and hydraulic band brakes (hereinafter referred to as clutches and brakes, respectively). In an automatic transmission of this type, a shift position connection is changed from a first speed to a second speed by releasing one(s) of the friction engaging elements associated with the first speed and by engaging another friction engaging element(s) associated with the second speed, to select gears which contribute to torque transmission, to thereby establish a desired shift position.
In recent years, in order to improve the drivability of automobiles and reduce the fuel consumption, attempts are made to further enhance the degree of electronic control for the automatic transmission and increase the number of shift positions or transmission stages. A typical multistage automatic transmission includes a main transmission mechanism having an existing transmission mechanism and a subsidiary transmission mechanism coupled in line, with respect to torque transmission, with the main transmission mechanism. Those two transmission mechanisms which contribute to torque transmission are combined in various manners, to thereby establish an arbitrary one of a required number of shift positions, e.g., five forward speeds and one reverse speed. For example, the speed position in the main transmission mechanism is changed over to effect a speed-changing operation among a first speed, a second speed, and a third speed, and the speed position in the subsidiary transmission mechanism is changed over to effect a speed-changing operation between the third speed and a fourth speed. Further, to carry out a speed-changing between the fourth speed and a fifth speed, the speed position in the main transmission mechanism is changed over, with the gear engagement state (torque transmission path) in the subsidiary transmission mechanism set to correspond to the fourth speed. In other words, by use of the subsidiary transmission mechanism, a switching is made between the lower-speed shift positions including the first through third speeds and the higher-speed shift positions including the fourth and fifth speeds.
In an electronic controlled automatic transmission, a shift map determined as a function of vehicle speed and a throttle valve opening degree, as shown in FIG. 8, is generally used to select a shift position. From this map, an optimum shift position (target shift position) suitable to detected values of the vehicle speed and throttle valve opening degree is selected. In the case of a kick-down at a rapid acceleration, the target shift position is generally determined by the throttle valve opening degree. That is, when the throttle valve opening degree traverses the 5-4 shift line or 4-3 shift line as shown in FIG. 8, a down-shift command is output. As a result, if the accelerator pedal is depressed by the driver and the throttle valve opening degree .theta. reaches the point B from the point A in FIG. 8, a down-shift is carried out from the fifth speed to the fourth speed. When the throttle valve opening degree .theta. reaches the point C from the point A, a so-called skip down-shift from the fifth speed to the third speed is effected.
On an occasion that a skip down-shift from the fifth speed to the third speed is effected in the aforementioned multi-stage automatic transmission, it is necessary to make the changeover of speed positions in both of the main and subsidiary transmission mechanisms. How
REFERENCES:
patent: 4674364 (1987-06-01), Shindo et al.
patent: 4733580 (1988-03-01), Kubo et al.
patent: 5038286 (1991-08-01), Asayama et al.
patent: 5094130 (1992-03-01), Hirose et al.
patent: 5345843 (1994-09-01), Fujita et al.
patent: 5370016 (1994-12-01), Fujita et al.
patent: 5435796 (1995-07-01), Fujita et al.
patent: 5439427 (1995-08-01), Enokido et al.
patent: 5443432 (1995-08-01), Fujita et al.
patent: 5445577 (1995-08-01), Fujita et al.
patent: 5445579 (1995-08-01), Fujita et al.
patent: 5460583 (1995-10-01), Kitada et al.
Fujita Kenjiro
Tashiro Tetsuya
Usuki Katsutoshi
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
Ta Khoi Q.
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