# US 2012/0073929 A1 · All Wheel Drive Speed Synchronization and Connection

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- Number: US 2012/0073929 A1
- Document ID: US20120073929A1
- Status: Published application
- Kind: A1
- Application number: 12/891,871
- Filed: 2010-09-28
- Published: 2012-03-29
- Earliest claimed: 2010-09-28
- Assignees: Ford Global Technologies, LLC
- Inventors: Peter J. Grutter; Andreas E. Perakes; Nicholas E. McCubbin; Ashok E. Rodrigues; Robert S. Lippert
- Web page: https://patentgrep.com/patent/US20120073929A1

## CPC

- F16D 23/06: and a blocking mechanism preventing the engagement of the main clutch prior to synchronisation
- B60K 17/344: having a transfer gear
- B60K 23/08: for changing number of driven wheels {, for switching from driving one axle to driving two or more axles (B60K17/3515 takes precedence)}
- B60K 23/0808: {for varying torque distribution between driven axles, e.g. by transfer clutch}
- F16D 2023/0693: {Clutches with hydraulic actuation}
- F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES

## Abstract

A vehicle driveline includes a power source, a transmission connected to the power source and including an output driveably connected to primary road wheels, a driveshaft, a synchronizer that opens and closes a drive connection between the output and the driveshaft, and a clutch that alternately opens and closes a drive connection between the driveshaft and secondary road wheels. A control executes synchronization and connection strategies using one of singular, overlapping and sequential activation of the driveline components that produce all-wheel-drive on-demand.

## Claims

### Claim 1

A method for engaging all-wheel drive operation in a vehicle driveline, comprising:
using a clutch of a rear-drive-unit to accelerate driveline components toward a speed of secondary wheels;
disengaging the clutch;
using a synchronizer of a power-transfer unit to accelerate said components toward a speed of a transmission output;
engaging the synchronizer to transmit torque between the transmission output and the clutch;
increasing a torque capacity of the clutch.

### Claim 2 (depends on 1)

The method of claim 1, further comprising limiting a torque transmitting capacity of the clutch.

### Claim 3 (depends on 1)

The method of claim 1, further comprising limiting a rate of change of a torque transmitting capacity of the clutch.

### Claim 4

A method for engaging all-wheel drive operation in a vehicle driveline, comprising:
using a clutch of a rear-drive-unit to accelerate driveline components toward a speed of secondary wheels;
using a synchronizer of a power-transfer unit to accelerate the components toward a speed of a transmission output;
disengaging the clutch;
engaging the synchronizer to transmit torque between the transmission output and the clutch;
reengaging the clutch.

### Claim 5 (depends on 4)

The method of claim 4, further comprising limiting a torque transmitting capacity of the clutch.

### Claim 6 (depends on 4)

The method of claim 4, further comprising limiting a rate of change of a torque transmitting capacity of the clutch.

### Claim 7

A method for engaging all-wheel drive operation in a vehicle driveline, comprising:
using a synchronizer of a power-transfer unit to accelerate driveline the components toward a speed of a transmission output;
using the synchronizer to transmit torque between the transmission output and a clutch of a rear-drive-unit;
engaging the clutch to transmit torque to secondary road wheels.

### Claim 8

A vehicle driveline comprising:
a power source;
a transmission connected to the power source and including an output driveably connected to primary road wheels;
a driveshaft;
a synchronizer that opens and closes a drive connection between the output and the driveshaft;
a clutch that alternately opens and closes a drive connection between the driveshaft and secondary road wheels.

### Claim 9 (depends on 8)

The driveline of claim 8, further comprising:
a bevel ring gear secured to an output of the synchronizer;
a bevel pinion gear meshing with the ring gear, the driveshaft connected to the pinion gear.

### Claim 10 (depends on 8)

The driveline of claim 8, further comprising:
a differential mechanism driveably connected to the transmission output for transmitting rotating power to the primary road wheels.

### Claim 11 (depends on 8)

The driveline of claim 8, further comprising:
a second differential mechanism driveably connected to an output of the clutch for transmitting rotating power to the secondary road wheels.