Shift control method and apparatus of an automatic transmission

• US 20050075776A1
• Filed: 07/24/2003
• Published: 04/07/2005
• Est. Priority Date: 11/28/2002
• Status: Active Grant

• Current Assignee: Hyundai Motor Company (Hyundai Motor Group)
• Original Assignee: Hyundai Motor Company (Hyundai Motor Group)
• Inventors: Cho, Young Shin
• Granted Patent: US 6,950,736 B2
• Time in Patent Office: Days
• US Class Current: 701/62
• CPC Class Codes: F16H 2061/1224 Adapting to failures or work around with other constraints, e.g. circumvention by avoiding use of failed parts
• CPC Class Codes: F16H 2061/1268 Electric parts of the controller, e.g. a defect solenoid, wiring or microprocessor
• CPC Class Codes: F16H 2061/1284 the failing part is a sensor
• CPC Class Codes: F16H 59/105 consisting of electrical switches or sensors
• 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

Abstract

In the case of malfunctioning of an inhibitor switch of an automatic transmission, a current vehicle speed is compared with a maximum vehicle speed of a reverse speed when the current vehicle speed is other than 0. The transmission is then controlled to a target shift-speed determined on the basis of vehicle driving state parameters, when the current vehicle speed is higher than the maximum vehicle speed of the reverse speed.

Claims

1. A shift control method of an automatic transmission, comprising:

determining if an inhibitor switch is malfunctioning;

detecting a current vehicle speed when the inhibitor switch is malfunctioning;

determining if the current vehicle speed equals 0;

obtaining a maximum vehicle speed of the reverse R range when the current vehicle speed does not equal 0;

comparing the current vehicle speed with the maximum vehicle speed of the reverse R range;

determining a target shift-speed on the basis of vehicle driving state parameters when the current vehicle speed is higher than the maximum speed of the reverse R range; and

controlling actuators of the transmission such that the target shift-speed is engaged.

2. The shift control method of claim 1, wherein in the determining of the target shift-speed, the target shift-speed is selected from shift-speeds of the transmission excluding the first forward speed.

3. The shift control method of claim 1, wherein the vehicle driving state parameters include a vehicle speed and a degree of accelerator operation.

4. The shift control method of claim 1, further comprising:

determining, in the case that the inhibitor switch is malfunctioning, if other sensors or the actuators of the transmission are malfunctioning; and

determining the target shift-speed as a predetermined shift-speed when other sensors or the actuators of the transmission are malfunctioning such that the predetermined shift-speed is engaged by the controlling of actuators.

5. A shift control apparatus of an automatic transmission, comprising:

an inhibitor switch for detecting a shift range designated by a driver;

a vehicle speed detector for detecting vehicle speed;

an accelerator position detector for detecting a degree of accelerator operation;

actuators for executing shifting operation of the automatic transmission; and

a transmission control unit for controlling the actuators based on a target shift-speed that is determined on the basis of input signals from the inhibitor switch, the vehicle speed detector, and the accelerator position detector,

wherein the transmission control unit executes a set of instructions, the set of instructions comprising instructions for;

determining if an inhibitor switch is malfunctioning;

detecting a current vehicle speed when the inhibitor switch is malfunctioning;

determining if the current vehicle speed equals 0;

obtaining a maximum vehicle speed of the reverse R range when the current vehicle speed does not equal 0;

comparing the current vehicle speed with the maximum vehicle speed of the reverse R range;

determining a target shift-speed on the basis of vehicle driving state parameters when the current vehicle speed is higher than the maximum speed of the reverse R range; and

controlling actuators of the transmission such that the target shift-speed is engaged.

6. The shift control apparatus of claim 5, wherein in the determining of the target shift-speed, the target shift-speed is selected from shift-speeds of the transmission excluding the first forward speed.

7. The shift control apparatus of claim 5, wherein the vehicle driving state parameters include a vehicle speed and a degree of accelerator operation.

8. The shift control apparatus of claim 5, wherein the set of instructions further comprises:

determining, in the case that the inhibitor switch is malfunctioning, if other sensors or the actuators of the transmission are malfunctioning; and

determining the target shift-speed as a predetermined shift-speed when other sensors or the actuators of the transmission are malfunctioning such that the predetermined shift-speed is engaged by the controlling of actuators.