Shift control method and system for automatic transmission
AssigneeMazda Motor Corporation
InventorsAkio Matsumoto, Junichi Doi, Tomoo Sawazaki
Life of this patent
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Abstract
An automobile automatic transmission shift control system, for causing a specific gear shift by unlocking a first frictional element with a simultaneously with locking a second frictional element, discharges locking pressure from the first frictional element in such a way that the locking pressure is throttled after it has dropped below a specified level of pressure.
Claims13
In a shift control system for an automatic transmission having a plurality of hydraulically operated frictional elements for an automotive vehicle for selectively locking and unlocking said hydraulically operated frictional elements so as to automatically perform gear shifts according to vehicle driving conditions, a specific one of said gear shifts being executed by unlocking a first specific hydraulically operated frictional element of said hydraulically operated frictional elements simultaneously with locking a second specific hydraulically operated frictional element of said hydraulically operated frictional elements, the improvement comprising:
- a hydraulic control circuit for supplying and releasing pressurized hydraulic oil for locking and unlocking to said hydraulically operated frictional elements, said hydraulic control circuit including pressure control means for allowing said locking oil pressure to be discharged from said first specific hydraulically operated frictional element without being throttled until said locking oil pressure drops to a specified level of pressure and throttling said locking oil pressure discharged from said first specific hydraulically operated frictional element after said locking pressure has dropped below said specified level of pressure.
In a method of controlling gear shifts for an automatic transmission having a plurality of hydraulically operated frictional elements for an automotive vehicle in which said hydraulically operated frictional elements are selectively locked and unlocked so as to automatically perform gear shifts according to vehicle driving conditions, a specific one of said gear shifts being executed by unlocking a first specific hydraulically operated frictional element of said hydraulically operated frictional elements simultaneously with locking a second specific hydraulically operated frictional element of said hydraulically operated frictional elements, the improvement comprising:
- discharging locking oil pressure from said first specific hydraulically operated frictional element through an oil pressure control valve without throttling it until said locking oil pressure drops to a specified level of pressure, and with throttling it after said locking pressure has dropped below said specified level of pressure.
Dependencies are inferred from the claim text.