# US 10,480,647 B2 · Techniques for controlling pedal-off downshifts of a vehicle transmission

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- Number: US 10,480,647 B2
- Document ID: US10480647B2
- Status: Granted
- Kind: B2
- Application number: 15/901,478
- Filed: 2018-02-21
- Published: 2019-08-22
- Granted: 2019-11-19
- Earliest claimed: 2018-02-21
- Assignees: Fca US LLC
- Applicants: Steven B Christ; Stephen Tokish; Quan Zheng
- Inventors: Steven B Christ; Stephen Tokish; Quan Zheng
- Web page: https://patentgrep.com/patent/US10480647B2

## CPC

- F16H 61/08: Timing control
- F16H 61/0204: {for gearshift control, e.g. control functions for performing shifting or generation of shift signal}
- F16H 61/0213: {characterised by the method for generating shift signals}
- F16H 61/0437: {by using electrical signals (F16H61/0403 and F16H61/061 take precedence)}
- B60W 10/11: Stepped gearings
- B60W 30/18072: {Coasting}
- B60W 30/19: Improvement of gear change, e.g. by synchronisation or smoothing gear shift
- B60W 2050/0026: {Lookup tables or parameter maps}
- B60W 2510/1015: Input shaft speed, e.g. turbine speed
- B60W 2510/1045: Output speed change rate
- B60W 2710/10: Change speed gearings
- F16H 59/40: Output shaft speed
- F16H 59/48: Inputs being a function of acceleration
- F16H 2059/186: {Coasting}
- F16H 2059/385: {Turbine speed}
- F16H 2059/405: {Rate of change of output shaft speed or vehicle speed}
- F16H 2061/0234: {Adapting the ratios to special vehicle conditions}
- F16H 2061/0459: {using map for shift parameters, e.g. shift time, slip or pressure gradient, for performing controlled shift transition and adapting shift parameters by learning}
- 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 transmission control system and method involve receiving, by a controller and from a turbine shaft speed sensor, a rotational speed of a turbine shaft of an automatic transmission, receiving, by the controller and from an output shaft speed sensor, a plurality of rotational speeds of an output shaft of the transmission, determining, by the controller, a shift time modifier based on the turbine shaft speed and a gradient of the output shaft speed, modifying, by the controller, a shift time for a pedal-off downshift of the transmission based on the shift time modifier to obtain a modified shift time, and controlling, by the controller, the pedal-off downshift of the transmission based on the modified shift time.

## Claims

### Claim 1

A control system for a transmission of a vehicle, the system comprising:
a turbine shaft speed sensor configured to measure a rotational speed of a turbine shaft of the transmission;
an output shaft speed sensor configured to measure a rotational speed of an output shaft of the transmission; and
a controller configured to:
determine a shift time modifier based on the turbine shaft speed and a gradient of the output shaft speed;
modify a shift time for a pedal-off downshift of the transmission based on the shift time modifier to obtain a modified shift time; and
control the pedal-off downshift of the transmission based on the modified shift time,
wherein the control of the pedal-off downshift based on the modified shift time achieves a smoother and consistent pedal-off downshift operation compared to other transmission downshift operations of the vehicle without such control.

### Claim 2 (depends on 1)

The system of claim 1, wherein a gradient of the turbine shaft speed remains approximately constant.

### Claim 3 (depends on 1)

The system of claim 1, wherein the controller is configured to utilize a two-dimensional lookup table that relates various shift time modifiers to various turbine shaft speeds and output shaft speed gradients.

### Claim 4 (depends on 3)

The system of claim 3, wherein larger turbine shaft speeds and larger output shaft speed gradients each correspond to larger shift time modifiers.

### Claim 5 (depends on 3)

The system of claim 3, wherein the modified shift time is less than the shift time.

### Claim 6 (depends on 1)

The system of claim 1, wherein the transmission is a front-wheel drive dog clutch nine-speed transmission.

### Claim 7

A method for performing a gear shift of a transmission of a vehicle, the method comprising:
receiving, by a controller and from a turbine shaft speed sensor, a rotational speed of a turbine shaft of the transmission;
receiving, by the controller and from an output shaft speed sensor, a plurality of rotational speeds of an output shaft of the transmission;
determining, by the controller, a shift time modifier based on the turbine shaft speed and a gradient of the output shaft speed;
modifying, by the controller, a shift time for a pedal-off downshift of the transmission based on the shift time modifier to obtain a modified shift time; and
controlling, by the controller, the pedal-off downshift of the transmission based on the modified shift time so as to achieve a smoother and consistent pedal-off downshift operation as compared to other transmission downshift operations of the vehicle without such control.

### Claim 8 (depends on 7)

The method of claim 7, wherein a gradient of the turbine shaft speed remains approximately constant.

### Claim 9 (depends on 7)

The method of claim 7, wherein determining the shift time modifier includes utilizing, by the controller, a two-dimensional lookup table that relates various shift time modifiers to various turbine shaft speeds and output shaft speed gradients.

### Claim 10 (depends on 9)

The method of claim 9, wherein larger turbine shaft speeds and larger output shaft speed gradients each correspond to larger shift time modifiers.

### Claim 11 (depends on 9)

The method of claim 9, wherein the modified shift time is less than the shift time.

### Claim 12 (depends on 7)

The method of claim 7, wherein the transmission is a front-wheel drive dog clutch nine-speed transmission.