Pre-charge control system of automatic transmission

In an automatic transmission including a plurality of friction elements which are selectively engageable to establish various gear speeds, a gear change system which, upon issuance of a gear change instruction, applies hydraulic pressure to selected one of said friction elements to induce an engaged condition of the same thereby to establish a certain gear speed and a pre-charge system which, for quickening starting of engaging stroke of the selected friction element in the gear change operation, raises an instruction value of hydraulic pressure for said selected friction element to a pre-charge pressure value upon issuance of said gear change instruction and keeps said instruction value at said pre-charge pressure value for a pre-charge period,

• a pre-charge control system for controlling operation of said pre-charge system, comprising:
• a first section which receives first and second gear change instructions which are issued in succession, said first and second gear change instructions being of a type of needing an engaged condition of said selected friction element;
• and
• a second section which, when said second gear change instruction is issued during a pre-charge period of said selected friction element which is needed by said first gear change instruction, extends the pre-charge period of said friction element to a time when a pre-charge period needed by said second gear change instruction lapses.