Clutch control device for 4-wheel drive vehicle

Patent metadata

Field	Value
Publication number	US-9688142-B2
Application number	US-201515117914-A
Country	US
Kind code	B2
Filing date	Feb 24, 2015
Priority date	Feb 27, 2014
Publication date	Jun 27, 2017
Grant date	Jun 27, 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 dog clutch and the friction clutch. The controller starts the engagement of the dog clutch, after placing the dog clutch in a rotationally synchronized state by engaging the friction clutch and increasing an output rotation thereof, when there is a request to engage the dog clutch. In this clutch control device, the controller sets the engagement start timing of the friction clutch when a transition is made to the connected, four-wheel drive mode to an earlier timing compared to when a transition is made to the standby two-wheel drive mode, when there is a request to engage the dog clutch while in a state in which the disconnected, two-wheel drive mode is selected.

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 a 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 a control of starting an engagement of the dog clutch, which is in a disengaged state, after putting the dog clutch into a rotationally synchronized state by engaging the friction clutch, in response to a request to engage the dog 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, a standby two-wheel drive mode in which the dog clutch is engaged and the friction clutch is disengaged, and a connected, four-wheel drive mode in which the dog clutch and the friction clutch are engaged, and
the clutch controller being programmed to set an engagement start timing of the friction clutch when a transition is made to the connected, four-wheel drive mode to an earlier timing as compared to when a transition is made to the standby two-wheel drive mode, in response to a request to engage the dog clutch while in a state in which the disconnected, two-wheel drive mode is selected.

2. The clutch control device as recited in claim 1 , wherein
the clutch controller sets the disconnected, two-wheel drive mode in a low accelerator position opening amount and high vehicle speed region, sets the standby two-wheel drive mode in a high accelerator position opening amount and high vehicle speed region, and sets the connected, four-wheel drive mode in an all accelerator position opening amount and low vehicle speed region.

3. The clutch control device as recited in claim 1 , wherein
the friction clutch comprises a clutch chamber that houses a multi-plate friction clutch, an oil chamber that is partitioned from the clutch chamber by a partition wall, an oil flow channel that fluidly communicates the clutch chamber with the oil chamber and conveys lubrication oil from the clutch chamber to the oil chamber by centrifugal force, and an open/close valve provided on the partition wall, and
the clutch controller, in response to a request to engage the dog clutch at a time of switching from the disconnected, two-wheel drive mode to the connected, four-wheel drive mode, immediately starts engagement of the friction clutch without waiting for the oil in the oil chamber to flow into the clutch chamber via the open/close valve.

4. The clutch control device as recited in claim 3 , wherein
the clutch controller, in response to request to engage the dog clutch at a time of switching from the disconnected, two-wheel drive mode to the standby two-wheel drive mode, starts engagement of the friction clutch after waiting for the oil in the oil chamber to flow into the clutch chamber via the open/close valve.

5. 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.

6. 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.

7. The clutch control device according to claim 2 , wherein
the friction clutch comprises a clutch chamber that houses a multi-plate friction clutch, an oil chamber that is partitioned from the clutch chamber by a partition wall, an oil flow channel that fluidly communicates the clutch chamber with the oil chamber and conveys lubrication oil from the clutch chamber to the oil chamber by centrifugal force, and an open/close valve provided on the partition wall, and
the clutch controller, in response to a request to engage the dog clutch at a time of switching from the disconnected, two-wheel drive mode to the connected, four-wheel drive mode, immediately starts engagement of the friction clutch without waiting for the oil in the oil chamber to flow into the clutch chamber via the open/close valve.

8. The clutch control device according to claim 7 , wherein
the clutch controller, in response to request to engage the dog clutch at a time of switching from the disconnected, two-wheel drive mode to the standby two-wheel drive mode, starts engagement of the friction clutch after waiting for the oil in the oil chamber to flow into the clutch chamber via the open/close valve.

9. 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.

10. 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.

11. The clutch control device according to claim 3 , 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.

12. The clutch control device according to claim 3 , 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.

13. The clutch control device according to claim 4 , 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.

14. The clutch control device according to claim 4 , 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 s

Assignees

• Nissan Motor

Inventors

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

Classifications

• F16D48/00

  External control of clutches · CPC title

• B60K2023/0825

  for adding torque to the front wheels · CPC title

• F16D2300/02

  Overheat protection, i.e. means for protection against overheating · CPC title

• B60K17/344

  having a transfer gear · CPC title

• B60K17/02

  characterised by arrangement, location, or kind of clutch · CPC title