Control device of automatic transmission

• US 6,361,464 B1
• Filed: 06/21/2000
• Issued: 03/26/2002
• Est. Priority Date: 06/25/1999
• Status: Expired due to Fees

• Current Assignee: Transtechnology Ltd.
• Original Assignee: Jatco Transtechnology Limited
• Inventors: Yoneyama, Nobuyuki
• Primary Examiner(s): Estremsky, Sherry
• Assistant Examiner(s): Lewis, Tisha D.
• Application Number:
  US09/598,611
• Time in Patent Office: 643 Days
• Field of Search: 475/116, 475/118, 475/119, 475/121, 475/127, 475/128
• US Class Current: 475/116
• CPC Class Codes: F16H 2061/1232 Bringing the control into a predefined state, e.g. giving priority to particular actuators or gear ratios
• CPC Class Codes: F16H 2061/1268 Electric parts of the controller, e.g. a defect solenoid, wiring or microprocessor
• CPC Class Codes: F16H 2306/00 Shifting
• CPC Class Codes: F16H 2312/022 Preparing to drive off
• CPC Class Codes: F16H 61/0206 Layout of electro-hydraulic control circuits, e.g. arrangement of valves for control of actuators selecting and moving final output members, e.g. shift forks F16H61/2807
• CPC Class Codes: F16H 61/12 Detecting malfunction or potential malfunction, e.g. fail safe in control of hydrostatic gearing F16H61/4192; Circumventing or fixing failures
• CPC Class Codes: F16H 61/21 Providing engine brake control
• CPC Class Codes: F16H 61/686 with orbital gears

Abstract

A control device of an automatic transmission has automatic shift ranges and manual setting ranges including a first speed gear position at which an engine brake is operable. The control device turns on all solenoid valves at the first speed gear position in the automatic shift driving range, turns on only the second and third solenoid valves at the first speed gear position in the manual setting range, and turns on at least one of the three solenoid valves in normal operation. This prevents a shock resulting from a shift and easily starts a vehicle even if all of the three solenoid valves supplying oil pressure to the first through third shift valves for changing gear positions are turned off. Oil channels are preset in such a manner as to achieve a high speed gear position if no oil pressure is supplied to all shift valves. If all solenoid valves are turned off in the manual setting range, low speed gear position selecting oil channels supplied with an oil pressure from a manual valve are connected to the second and third shift valves through a failsafe valve so that the gear position can be shifted to the first speed gear position at which the engine brake is operable.

Claims

1. A control device of an automatic transmission, which has an automatic shift range for automatically selecting a gear position according to driving conditions of a vehicle, and manual setting ranges for manually changing gear positions and having at least a low speed engine brake range in which the vehicle is driven at a lowest speed gear position with an engine brake being operable, said control device of the automatic transmission comprising:

an operating pressure control circuit for controlling an operating pressure supplied to and released from friction elements for selectively changing power transmission routes of a transmission mechanism;

wherein said operating pressure control circuit comprises;

a plurality of shift valves for changing supply and release channels for supplying and releasing the operating pressure to and from said friction elements according to the selected gear position;

first signal pressure generating means for supplying and releasing a signal pressure for controlling shift positions of said shift valves;

shift control means for controlling said first signal pressure generating means according to the selected gear position;

second signal pressure generating means for supplying a low speed range signal pressure if a low speed engine brake range is manually designated;

first fail range achieving means for achieving a lowest speed gear position at which the vehicle is driven with the engine brake being operable if said shift control means fails and if said second signal pressure generating means supplies a low speed range signal pressure; and

second fail range achieving means for achieving a predetermined gear position other than low speed gear positions if said shift control means fails and if said second signal pressure generating means does not supply said low speed range signal pressure.

2. A control device of an automatic transmission, which has automatic shift ranges for automatically selecting a gear position according to driving conditions of a vehicle, and a manual setting range for manually changing gear positions and having at least a low speed engine brake range in which the vehicle is driven at a lowest speed gear position with an engine brake being operable, said control device of the automatic transmission comprising:

a first shift valve, a second shift valve and a third shift valve for changing the connecting state of oil channels supplying an oil pressure to friction elements for setting the gear position;

a first switching oil channel for supplying an oil pressure for changing the connecting state of said first shift valve;

a first solenoid valve that is on-off controlled in such a manner as to supply an oil pressure to said first switching oil channel in a state of being on;

a second switching oil channel for supplying an oil pressure for changing the connecting state of said second shift valve;

a second solenoid valve that is on-off controlled in such a manner as to supply an oil pressure to said second switching oil channel in a state of being on in normal operation;

a third switching oil channel for supplying an oil pressure for changing the connecting state of said third shift valve;

a third solenoid valve that is ON-OFF controlled in such a manner as to supply an oil pressure to said third switching oil channel in a state of being on in normal operation;

a shift control part for controlling the ON/OFF state of said first, second and third solenoid valves according to a designated range in such a manner as to turn on said first, second and third solenoid valves if the lowest speed gear position is selected in said automatic shift driving range, and turn off said first solenoid valve and turn on said second and third solenoid valves if the lowest speed gear position at which the vehicle is driven with the engine brake being operable is selected;

said shift control part turning on at least one of said first, second and third solenoid valves in normal operation;

a manual valve for selectively connecting oil pressure sources to oil channels by manual operation;

a low speed gear position selecting channels which is supplied with an oil pressure from said manual valve when said low speed engine brake range is selected;

a failsafe valve for connecting said low speed gear position selecting channels with said second and third switching oil channels if said first, second and third solenoid valves are turned off; and

wherein said first, second and third shift valves connect to said friction elements in such a manner as to set a predetermined gear position other than the lower speed gear positions if the oil pressure is not supplied to the first, second and third switching oil channels.

3. A control device of an automatic transmission according to claim 2, wherein:

said automatic shift driving range includes a first speed gear position as the lowest speed gear position that is set by supplying the oil pressure to said first switching oil channel, said second switching oil channel and said third switching oil channel, and has a second speed through a fifth speed gear position as a highest speed gear position according to such a combination that the oil pressure is supplied to at least one of said first, second and third switching oil channels; and

said first shift valve, said second shift valve and said third shift valve connect to friction elements in such a manner as to form oil pressure routes for supplying the oil pressure to friction elements which are engaged in a fourth speed gear position if no oil pressure is supplied to all of said first, second and third switching oil channels.