초록 ▼

In a control device of an automatic transmission that controls a plurality of solenoid valves by an ATCU to thereby supply and release signal pressure for controlling friction elements according to selected gear positions, the solenoid valves generate a signal pressure to be supplied to the friction

In a control device of an automatic transmission that controls a plurality of solenoid valves by an ATCU to thereby supply and release signal pressure for controlling friction elements according to selected gear positions, the solenoid valves generate a signal pressure to be supplied to the friction elements which are engaged at a predetermined gear position in a low speed gear position group, when the ATCU stops functioning while the vehicle is driven at a low speed gear position. Shift valves supply the signal pressure to the friction elements. If the ATCU stops functioning while a gear position in a high speed gear position group is selected, the shift valves supply a signal pressure generated by manual valve to friction elements which are engaged at a predetermined gear position in the high speed gear position group. Thus, if the ATCU stops functioning while the vehicle is running, the gear position is fixed at a gear position at which a vehicle has been driven or is shifted up in order to prevent the deterioration of driving performance resulting from a down-shift.

대표청구항 ▼

1. A control device of an automatic transmission, which comprises a plurality of gear position selecting signal pressure generating means (SA, SB, SC, SD) that supplies and releases signal pressure for controlling engagement and disengagement of a plurality of friction elements, and shift control me

1. A control device of an automatic transmission, which comprises a plurality of gear position selecting signal pressure generating means (SA, SB, SC, SD) that supplies and releases signal pressure for controlling engagement and disengagement of a plurality of friction elements, and shift control means (41) that controls the gear position selecting signal pressure generating means according to gear positions selected by an automatic shift or a manual shift in order to achieve a plurality of forward driving gear positions by engagement and disengagement of the plurality of friction elements, wherein:the plurality of forward driving gear positions comprises at least a low speed gear position group composed of multiple forward driving gear positions including a lowest speed gear position and a high speed gear position group composed of multiple forward driving gear positions with higher speeds than the low speed gear position group; the plurality of gear position selecting signal pressure generating means generates signal pressure to be supplied to friction elements (C1, C2), which are engaged at a predetermined gear position in the low speed gear position group, when the shift control means stops functioning; the control device of the automatic transmission comprises: high speed gear position signal pressure generating means (43) that generates signal pressure to be supplied to friction elements (B2, C3), which are engaged at a predetermined gear position in the high speed gear position group; low speed gear position failsafe means (VA, VB, SE) that supplies the friction elements (C1, C2) which are engaged at the predetermined gear position in the low speed gear position group with the signal pressure generated by the gear position selecting signal pressure generating means if said shift control means stops functioning when said shift control means selects a gear position in said low speed gear position group; and high speed gear position failsafe means (VA, VB, SE) that supplies said friction elements (B2, C3) which are engaged at the predetermined gear position in the high speed gear position group with the signal pressure generated by said high speed gear position signal pressure generating means if said shift control means stops functioning when said shift control means selects a gear position in said high speed gear position group.