Four-wheel drive vehicle

Patent metadata

Field	Value
Publication number	US-11072238-B2
Application number	US-201916391495-A
Country	US
Kind code	B2
Filing date	Apr 23, 2019
Priority date	Apr 23, 2018
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

A four-wheel drive vehicle in which, when a switching request is made for switching from a non-meshing state to a meshing state, the control device calculates a first rotation speed difference between the drive-power-source-side meshing teeth and the sub-drive-wheel-side meshing teeth, and a second rotation speed difference between the drive-power-source-side meshing teeth and the sub-drive-wheel-side meshing teeth. If at least one of the calculated first and second rotation speed differences is within a predetermined range set in advance, the control device couples the sub-drive wheel corresponding to the rotation speed difference within the predetermined range, to the central axle by the control coupling to switch the dog clutch from the non-meshing state to the meshing state. And, if neither the calculated first nor second rotation speed difference is within the predetermined range, the control device prohibits switching of the dog clutch from the non-meshing state to the meshing state.

First claim

What is claimed is:

1. A four-wheel drive vehicle selectively switching between a two-wheel drive state in which a drive power is transmitted from a drive power source to a pair of left and right main drive wheels and a four-wheel drive state in which the drive power is also transmitted from the drive power source to a pair of left and right sub-drive wheels through a power transmitting member for transmitting the drive power to the pair of left and right sub-drive wheels and disconnecting the power transmitting member from each of the drive power source and the pair of left and right sub-drive wheels in the two-wheel drive state,
the four-wheel drive vehicle comprising:
a pair of left and right control couplings respectively coupled to the pair of left and right sub-drive wheels; a central axle disposed between the paired left and right control couplings and coupled to the pair of left and right control couplings; a dog clutch selectively disconnecting or connecting a power transmission path between the drive power source and the power transmitting member or a power transmission path between the power transmitting member and the central axle; and a control device, wherein
the dog clutch includes drive-power-source-side meshing teeth coupled to the drive power source in a power transmittable manner and sub-drive-wheel-side meshing teeth coupled to the sub-drive wheels in a power transmittable manner, wherein
the drive-power-source-side meshing teeth and the sub-drive-wheel-side meshing teeth are provided with one-sided chamfers to allow the drive-power-source-side meshing teeth and the sub-drive-wheel-side meshing teeth to mesh with each other when a rotation speed of the drive-power-source-side meshing teeth is greater than a rotation speed of the sub-drive-wheel-side meshing teeth in a case that the drive-power-source-side meshing teeth and the sub-drive-wheel-side meshing teeth come closer to each other and cause respective tip portions to abut on each other, wherein
when a switching request is made for switching from a non-meshing state in which the drive-power-source-side meshing teeth are not meshed with the sub-drive-wheel-side meshing teeth to a meshing state in which the drive-power-source-side meshing teeth are meshed with the sub-drive-wheel-side meshing teeth, the control device calculates a first rotation speed difference between the drive-power-source-side meshing teeth and the sub-drive-wheel-side meshing teeth in a case that one of the pair of left and right sub-drive wheels is coupled to the central axle by corresponding one of the pair of left and right control couplings, and a second rotation speed difference between the drive-power-source-side meshing teeth and the sub-drive-wheel-side meshing teeth in the case that the other of the pair of left and right sub-drive wheels is coupled to the central axle by corresponding the other of the pair of left and right control couplings, wherein
if at least one of the calculated first and second rotation speed differences is within a predetermined range set in advance, the control device couples the sub-drive wheel corresponding to the rotation speed difference within the predetermined range, to the central axle by the control coupling to switch the dog clutch from the non-meshing state to the meshing state, and wherein
if neither the calculated first nor second rotation speed difference is within the predetermined range, the control device prohibits switching of the dog clutch from the non-meshing state to the meshing state.

2. The four-wheel drive vehicle according to claim 1 , wherein when both the first and second rotation speed differences are within the predetermined range, the control device selects the first rotation speed difference or the second rotation speed difference so that a smaller difference is selected out of a difference between a set rotation speed difference defined in advance and the first rotation speed difference and a difference between the set rotation speed difference and the second rotation speed difference, and couples the sub-drive wheel corresponding to the selected rotation speed difference, to the central axle by the control coupling.

3. The four-wheel drive vehicle according to claim 1 , wherein even if neither the first rotation speed difference nor the second rotation speed difference is within the predetermined range and it is determined that the dog clutch needs to be switched from the non-meshing state to the meshing state, the control device couples the sub-drive wheel corresponding to a larger value of the first rotation speed difference and the second rotation speed difference, to the central axle by the control coupling.

4. The four-wheel drive vehicle according to claim 1 , wherein
the dog clutch selectively disconnects or connects the power transmission path between the drive power source and the power transmitting member, wherein
the four-wheel drive vehicle comprises a first clutch selectively disconnecting or connecting the power transmission path in the power transmission path between the power transmitting member and the central axle, and wherein
when the sub-drive wheel is coupled to the central axle by the control coupling, the control device controls the dog clutch to connect the power transmission path between the drive power source and the power transmitting member and controls the first clutch to connect the power transmission path between the power transmitting member and the central axle.

5. The four-wheel drive vehicle according to claim 4 , wherein
the first clutch includes a first synchronizing mechanism synchronizing a rotation speed of a first rotating member coupled to the power transmitting member in a power transmittable manner and a rotation speed of a second rotating member coupled to the central axle in a power transmittable manner, and wherein
when the sub-drive wheel is coupled to the central axle by the control coupling and the rotation speed of the first rotating member is synchronized with the rotation speed of the second rotating member by the first synchronizing mechanism, the control device switches the dog clutch from the non-meshing state to the meshing state.

6. The four-wheel drive vehicle according to claim 1 , wherein
the dog clutch selectively disconnects or connects the power transmission path between the power transmitting member and the central axle, wherein
the four-wheel drive vehicle comprises a second clutch selectively disconnecting or connecting the power transmission path in the power transmission path between the drive power source and the power transmitting member, and wherein
when the sub-drive wheel is coupled to the central axle by the control coupling, the control device controls the dog clutch to connect the power transmission path between the power transmitting member and the central axle and controls the second clutch to connect the power transmission path between the drive power source and the power transmitting member.

7. The four-wheel drive vehicle according to claim 6 , wherein
the second clutch includes a second synchronizing mechanism synchronizing a rotation speed of a third rotating member coupled to the drive power source in a power transmittable manner and a rotation speed of a fourth rotating member coupled to the power transmitting member in a power transmittable manner, and wherein
when the sub-drive wheel is coupled to the central axle by the control coupling and the rotation speed of the third rotating member is synchronized with the rotation speed of the fourth rotating member by the second synchronizing mechanism, the control device switches the dog clutch from the non-meshing state to the meshing state.

Assignees

• Toyota Motor Co Ltd

Inventors

• Yuasa Ryohei
• Ishida Satoshi
• Murai Shota
• Goto Taito

Classifications

• B60K17/344

  having a transfer gear · CPC title

• B60K23/0808 Primary

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

• B60K17/3467

  combined with a change speed gearing, e.g. range gear · CPC title

• B60K17/02

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

• B60K17/34

  for driving both front and rear wheels, e.g. four wheel drive vehicles · CPC title