# US 8,751,122 B2 · Method for checking an emergency condition in a transmission system

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- Number: US 8,751,122 B2
- Document ID: US8751122B2
- Status: Granted
- Kind: B2
- Application number: 13/748,689
- Filed: 2013-01-24
- Published: 2013-08-01
- Granted: 2014-06-10
- Earliest claimed: 2012-01-26
- Assignees: ZF Friedrichshafen AG
- Applicants: ZF Friedrichshafen AG
- Inventors: Jorg Arnold; Michael Sohler; Klaus Steinhauser; Thilo Schmidt
- Web page: https://patentgrep.com/patent/US8751122B2

## CPC

- F16H 61/12: Detecting malfunction or potential malfunction, e.g. fail safe (in control of hydrostatic gearing F16H61/4192) {; Circumventing or fixing failures}
- B60W 10/11: Stepped gearings
- F16H 61/686: with orbital gears
- F16H 59/42: Input shaft speed
- F16H 59/46: dependent on a comparison between speeds
- F16H 2059/385: {Turbine speed}
- F16H 2061/1216: {Display or indication of detected failures}
- F16H 2061/1232: {Bringing the control into a predefined state, e.g. giving priority to particular actuators or gear ratios}
- F16H 2200/2094: using positive clutches, e.g. dog clutches
- F16H: GEARING
- B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT

## Abstract

A method of monitoring an emergency condition in an automatic transmission, with which, by comparing a theoretical with an actual rotational speed, measured on the transmission input side, overlap of the activated emergency condition, with a gear engagement process called for during the normal condition, is prevented.

## Claims

### Claim 1

A method of monitoring an emergency condition in an automatic transmission, the method comprising the steps of:
comparing a theoretical and an actual rotational speed that is measured on a transmission input side, and
preventing an overlap of the activated emergency condition, with a gear engagement process called for during normal condition, depending on the comparison.

### Claim 2 (depends on 1)

The method according to claim 1, further comprising the step of recognizing a fault condition, when there is a deviation between a stored theoretical curve and the actual curve of the rotational speed measured on the transmission input side, and
preventing activation of any further shifting element (A, D) if a fault condition is recognized.

### Claim 3 (depends on 1)

The method according to claim 1, further comprising the step of defining the rotational speed on the transmission input side as the rotational speed of a turbine of a torque converter on the transmission input side.

### Claim 4 (depends on 3)

The method according to claim 3, further comprising the step of recognizing a fault condition by a drop of the actual turbine rotational speed (n_t_Fault) in the automatic transmission before a predetermined point in time (T4).

### Claim 5 (depends on 1)

The method according to claim 1, further comprising the step of switching off an electronic transmission control system when a fault condition is recognized.

### Claim 6 (depends on 2)

The method according to claim 2, further comprising the step of, when a fault condition is recognized, permanently engaging a fail-safe gear in the automatic transmission until the fault condition is eliminated.

### Claim 7 (depends on 1)

The method according to claim 1, further comprising the step of issuing a warning message to a driver when a fault condition is recognized.

### Claim 8

A method of detecting an emergency condition in an automatic transmission of a vehicle, the method comprising the steps of:
monitoring actual turbine rotational speeds of a torque converter on an input side of the automatic transmission;
comparing the actual turbine rotational speed of the torque converter with stored theoretical turbine rotational speeds of the torque converter;
recognizing a fault condition when the actual turbine rotational speed of the torque converter deviates from the stored theoretical turbine rotational speeds of the torque converter; and
preventing an overlap of emergency operation of the automatic transmission and a gear engagement process, during normal operation of the automatic transmission, when the fault condition is recognized.

### Claim 9 (depends on 8)

The method according to claim 8, further comprising the step of preventing activation of any shifting element when the fault condition is recognized.

### Claim 10 (depends on 8)

The method according to claim 8, further comprising the step of switching off an electronic transmission control system when the fault condition is recognized.

### Claim 11 (depends on 8)

The method according to claim 8, further comprising the step of, when the fault condition is recognized, permanently engaging a fail-safe gear, in the automatic transmission, until the fault condition is eliminated.

### Claim 12 (depends on 8)

The method according to claim 8, further comprising the step of issuing a warning message to a driver of the vehicle when the fault condition is recognized.