Clutch control device for four-wheel drive vehicle

Patent metadata

Field	Value
Publication number	US-9758038-B2
Application number	US-201515117950-A
Country	US
Kind code	B2
Filing date	Feb 24, 2015
Priority date	Feb 27, 2014
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

A clutch control device is provided for a four-wheel drive vehicle for transmitting drive force to the rear wheels. The clutch control device includes a dog clutch and a friction clutch, and a controller that controls the engagement and disengagement of the dog clutch and the friction clutch. In this clutch control device, the four-wheel drive hybrid vehicle includes a disconnected, two-wheel drive mode and a connected, four-wheel drive mode. When a driver's foot is lifted off an accelerator in a low-speed region when the connected, four-wheel drive mode is selected, the 4WD control unit maintains the connected, four-wheel drive mode while the brakes are not depressed, and shifts the mode to the disconnected, two-wheel drive mode when the brakes are depressed.

First claim

The invention claimed is:

1. A clutch control device for a four-wheel drive vehicle having a pair of main drive wheels and a pair of auxiliary drive wheels which are selectively connected to the drive source, the clutch control device comprising:
a dog clutch operatively disposed in a transmission path between the main drive wheels and the auxiliary drive wheels to separate a system for transmitting drive force to the auxiliary drive wheels from a system for transmitting drive force to the main drive wheels by releasing the dog clutch;
a friction clutch operatively disposed in a transmission path between the main drive wheels and the auxiliary drive wheels to allocate a portion of the drive force from the drive source to the auxiliary drive wheels in accordance with a clutch engagement capacity of the friction clutch; and
a clutch controller operatively coupled to the dog clutch and the friction clutch to selectively carry out an engagement and disengagement control of the dog clutch and an engagement and disengagement control of the friction clutch,
the clutch controller being programmed to selectively establish a disconnected, two-wheel drive mode in which the dog clutch and the friction clutch are disengaged, and a connected, four-wheel drive mode in which the dog clutch and the friction clutch are engaged, and
the clutch controller, in response to a driver's foot being lifted off an accelerator while the connected, four-wheel drive mode is selected, being programmed to maintain the connected, four-wheel drive mode while brakes are not depressed, and to shift to the disconnected, two-wheel drive mode when the brakes are depressed.

2. The clutch control device as recited in claim 1 , wherein
the drive source comprises a motor/generator that carries out regenerative control during a brake depression operation.

3. The clutch control device according to claim 2 , wherein
the clutch controller is further programmed to carry out a control in which a disengagement request is issued to the dog clutch such that the dog clutch, which is in an engaged state, is disengaged after the friction clutch is disengaged upon determining the connected, four-wheel drive mode has been shifted to the disconnected, two-wheel drive mode based on a brake depression operation.

4. The clutch control device according to claim 2 , wherein
the clutch controller is further programmed to carry out a control in which an engagement request is issued to the dog clutch such that the dog clutch, which is in a disengaged state, is engaged after the dog clutch is placed in a rotationally synchronized state by engaging the friction clutch upon determining the driver's foot has been lifted off the brake after shifting to the disconnected, two-wheel drive mode due to a brake depression operation.

5. The clutch control device according to claim 2 , wherein
the dog clutch is disposed upstream of a transfer mechanism provided at a drive branch position to the auxiliary drive wheels, and
the friction clutch is disposed in a drive shaft of one of the auxiliary drive wheels which extends from the transfer mechanism that is connected to a propeller shaft and a differential.

6. The clutch control device according to claim 2 , wherein
the friction clutch is disposed upstream of a transfer mechanism provided at a drive branch position to the auxiliary drive wheels, and
the dog clutch is disposed in a drive shaft of one of the auxiliary drive wheels which extends from the transfer mechanism that is connected to a propeller shaft and a differential.

7. The clutch control device as recited in claim 1 wherein
the clutch controller is further programmed to carry out a control in which a disengagement request is issued to the dog clutch such that the dog clutch, which is in an engaged state, is disengaged after the friction clutch is disengaged upon determining the connected, four-wheel drive mode has been shifted to the disconnected, two-wheel drive mode based on a brake depression operation.

8. The clutch control device according to claim 7 , wherein
the clutch controller is further programmed to carry out a control in which an engagement request is issued to the dog clutch such that the dog clutch, which is in a disengaged state, is engaged after the dog clutch is placed in a rotationally synchronized state by engaging the friction clutch upon determining the driver's foot has been lifted off the brake after shifting to the disconnected, two-wheel drive mode due to a brake depression operation.

9. The clutch control device according to claim 7 , wherein
the dog clutch is disposed upstream of a transfer mechanism provided at a drive branch position to the auxiliary drive wheels, and
the friction clutch is disposed in a drive shaft of one of the auxiliary drive wheels which extends from the transfer mechanism that is connected to a propeller shaft and a differential.

10. The clutch control device according to claim 7 , wherein
the friction clutch is disposed upstream of a transfer mechanism provided at a drive branch position to the auxiliary drive wheels, and
the dog clutch is disposed in a drive shaft of one of the auxiliary drive wheels which extends from the transfer mechanism that is connected to a propeller shaft and a differential.

11. The clutch control device as recited in claim 1 , wherein
the clutch controller is further programmed to carry out a control in which an engagement request is issued to the dog clutch such that the dog clutch, which is in a disengaged state, is engaged after the dog clutch is placed in a rotationally synchronized state by engaging the friction clutch upon determining the driver's foot has been lifted off the brake after shifting to the disconnected, two-wheel drive mode due to a brake depression operation.

12. The clutch control device according to claim 11 , wherein
the dog clutch is disposed upstream of a transfer mechanism provided at a drive branch position to the auxiliary drive wheels, and
the friction clutch is disposed in a drive shaft of one of the auxiliary drive wheels which extends from the transfer mechanism that is connected to a propeller shaft and a differential.

13. The clutch control device according to claim 11 , wherein
the friction clutch is disposed upstream of a transfer mechanism provided at a drive branch position to the auxiliary drive wheels, and
the dog clutch is disposed in a drive shaft of one of the auxiliary drive wheels which extends from the transfer mechanism that is connected to a propeller shaft and a differential.

14. The clutch control device as recited in claim 1 , wherein
the dog clutch is disposed upstream of a transfer mechanism provided at a drive branch position to the auxiliary drive wheels, and
the friction clutch is disposed in a drive shaft of one of the auxiliary drive wheels which extends from the transfer mechanism that is connected to a propeller shaft and a differential.

15. The clutch control device as recited in claim 1 , wherein
the friction clutch is disposed upstream of a transfer mechanism provided at a drive branch position to the auxiliary drive wheels, and
the dog clutch is disposed in a drive shaft of one of the auxiliary drive wheels which extends from the transfer mechanism that is connected to a propeller shaft and a differential.

Assignees

• Nissan Motor

Inventors

• Ogawa Katsuyoshi
• Mori Atsuhiro
• Mitsuishi Shunichi
• Morita Makoto
• Takaishi Tetsu

Classifications

• F16D13/00

  Friction clutches (arrangements for synchronisation F16D23/02) · CPC title

• B60K23/0808

  for varying torque distribution between driven axles, e.g. by transfer clutch · CPC title

• B60W30/18127

  Regenerative braking · CPC title

• B60K23/08 Primary

  for changing number of driven wheels {, for switching from driving one axle to driving two or more axles (B60K17/3515 takes precedence)} · CPC title

• B60K17/3515

  with a clutch adjacent to traction wheel, e.g. automatic wheel hub · CPC title