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US 4,790,215 AGranted
Method and system for control of two part type transmission providing limited time for auxiliary transmission overdrive engagement with main transmission speed reduction engagement
AssigneeToyota Jidosha Kabushiki Kaisha
InventorYukio Hamano
Life of this patent
Estimating the term…
Abstract
In the control of a vehicle automatic transmission having a series connection of an overdrive gear mechanism and an underdrive gear mechanism, the overdrive gear being switched over between direct connection and overdrive both when the underdrive gear mechanism is switched to direct connection and to speed reduction, a maximum limit is set for the period over which the overdrive gear mechanism is switched to overdrive while the underdrive gear mechanism is switched to speed reduction, such a maximum period being determined according to a vehicle operational parameter such as vehicle speed, throttle opening or transmission fluid temperature.
Claims36
A transmission control method for an automatic transmission of a vehicle, said transmission comprising:
- (a) an auxiliary gear transmission mechanism, comprising a power input shaft and a power output shaft, and switchingly controllable to provide either a directly connected speed stage between its said power input shaft and its said power output shaft or a speed increasing overdrive speed stage between its said power input shaft and its said power output shaft, and;
- (b) a main gear transmission mechanism, comprising a power input shaft rotationally connected to said power output shaft of said auxiliary gear transmission mechanism and a power output shaft, and switchingly controllable to provide either a directly connected speed stage between its said power input shaft and its said power output shaft or at least one speed reducing speed stage between its said power input shaft and its said power output shaft;
- said method, comprising the steps of:
- (c) switching said auxiliary gear transmission mechanism between providing its said directly connected speed stage and providing its said speed increasing overdrive speed stage, both when said main gear transmission mechanism is switched to provide its said directly connected speed stage and when said main gear transmission mechanism is switched to its said speed reducing speed stage, so as to provide a series of speed stages of varying gear ratios by various combinations of said directly connected speed stage and said speed increasing overdrive speed stage of said auxiliary gear transmission mechanism and said directly connected speed stage and said speed reducing speed stage or stages of said main gear transmission mechanism, according to said vehicle operational parameters, and;
- (d) setting a maximum time limit period over which said auxiliary gear transmission mechanism is switched to provide its said speed increasing overdrive speed stage when said main gear transmission mechanism is switched to provide its said speed reducing speed stage, such a maximum period being determined according to a vehicle operational parameter.
2 more elements
A transmission control system for automatic transmission of a vehicle, said transmission comprising:
- (a) an auxiliary gear transmission mechanism, comprising a power input shaft and a power output shaft, and switchingly controllable to provide either a directly connected speed stage between its said power input shaft and its said power output shaft or a speed increasing overdrive speed stage between its said power input shaft and its said power output shaft, and;
- (b) a main gear transmission mechanism, comprising a power input shaft rotationally connected to said power output shaft of said auxiliary gear transmission mechanism and a power output shaft, and switchingly controllable to provide either a directly connected speed stage between its said power input shaft and its said power output shaft or at least one speed reducing speed stage between its said power input shaft and its said power output shaft;
- said system comprising:
- (c) a means for switching said auxiliary gear transmission mechanism between its said directly connected speed stage and its said speed increasing overdrive speed stage according to vehicle operational parameters, both when said main gear transmission mechanism is switched to its said directly connected speed stage and when said main gear transmission mechanism is switched to its said speed reducing speed stage, so as to provide a series of speed stages of varying gear ratios by various combinations of said directly connected speed stage and said speed increasing overdrive speed stage of said auxiliary gear transmission mechanism and said directly connected speed stage and said speed reducing speed stage or stages of said main gear transmission mechanism, and;
- (d) a means for setting a maximum limit period for which said auxiliary gear transmission mechanism is switched to provide its said speed increasing overdrive speed stage when said main gear transmission mechanism is switched to provide its said speed reducing speed stage, said maximum period being determined according to a vehicle operational parameter.
2 more elements
Dependencies are inferred from the claim text.