Vehicle power transmission device

Patent metadata

Field	Value
Publication number	US-2016101690-A1
Application number	US-201514873527-A
Country	US
Kind code	A1
Filing date	Oct 2, 2015
Priority date	Oct 8, 2014
Publication date	Apr 14, 2016
Grant date	—

Abstract

In a transfer, a high thrust can be given to a front-wheel driving clutch by a high magnification function of a screw mechanism. Further, a necessary stroke for an operation of a high-low switching mechanism can be obtained by the screw mechanism. Accordingly, with the use of one motor, the screw mechanism, and a transmission mechanism, it is possible to perform a switching operation of the high-low switching mechanism and a torque adjustment of the front-wheel driving clutch by the same system. Hereby, it is possible to perform, with accuracy, the switching operation of the high-low switching mechanism and the torque adjustment of the front-wheel driving clutch, based on a motor rotation angle Am of one motor.

First claim

What is claimed is:

1 . A power transmission device for a vehicle, the power transmission device comprising:
a transfer including
an input rotational member,
a first output rotational member configured to output a power to first right and left wheel assemblies,
a second output rotational member configured to output a power to second right and left wheel assemblies,
a high-low switching mechanism configured to change a speed of a rotation of the input rotational member and, the high-low switching mechanism being configured to transmit the rotation to the first output rotational member,
a clutch configured to adjust a transmission torque to be transmitted from the first output rotational member to the second output rotational member,
a motor,
a screw mechanism configured to convert a rotational motion of the motor into a linear motion,
a transmission mechanism configured to transmit a linear motion force of the screw mechanism to the high-low switching mechanism and the clutch, and
a rotation angle sensor configured to detect a rotation angle of the motor; and
at least one electronic control unit configured to perform a switching operation of the high-low switching mechanism and adjustment of the transmission torque of the clutch, based on the rotation angle of the motor.

2 . The power transmission device according to claim 1 , wherein
the electronic control unit is configured to
i) perform the adjustment of the transmission torque of the clutch by taking, as a reference point, a rotation angle of the motor at which the transmission torque of the clutch exceeds a predetermined value, and
ii) perform the switching operation of the high-low switching mechanism based on the reference point and a moving dimension in design in the linear motion of the screw mechanism.

3 . The power transmission device according to claim 2 , wherein
the electronic control unit is configured to
i) apply a predetermined current to the motor and rotate the motor such that the transmission torque of the clutch is generated, and
ii) determine, as the reference point, one of a) a rotation angle at a time when the rotation of the motor stops, b) a rotation angle obtained by further rotating the motor by a predetermined reference angle from the rotation angle at a time when the rotation of the motor stops, and c) a rotation angle of the motor at a time when the current applied to the motor increases by a predetermined reference current.

4 . The power transmission device according to claim 1 , wherein:
the screw mechanism includes
a rotational member connected to the motor, and
a rectilinearly-movable member connected to the rotational member in a movable manner in a direction parallel to a shaft center of the rotational member along with a rotation of the rotational member;
the high-low switching mechanism includes
high-gear teeth configured to output a rotation,
low-gear teeth configured to output a rotation at a lower speed than the high-gear teeth, and
a high-low sleeve splined to the first output rotational member such that the high-low sleeve meshes with the high-gear teeth and the low-gear teeth along with a movement in a direction parallel to a shaft center of the first output rotational member; and
the transmission mechanism includes
a pressing member connected to the rectilinearly-movable member such that the pressing member presses the clutch,
a fork shaft provided around another shaft center parallel to the shaft center of the rotational member and the fork shaft being connected to the rectilinearly-movable member, and
a fork secured to the fork shaft and the fork being connected to the high-low sleeve.

5 . The power transmission device according to claim 4 , wherein:
the transfer includes
lock teeth provided in the second output rotational member, and
a dog clutch having a lock sleeve, the lock sleeve splined to the first output rotational member, so as to mesh with the lock teeth along with a movement in the direction parallel to the shaft center of the first output rotational member; and
the transmission mechanism is configured to transmit the linear motion force of the screw mechanism to the lock sleeve via the high-low sleeve.

6 . The power transmission device according to claim 5 , wherein:
the high-low sleeve is provided in a space on a second-output-rotational-member side relative to a support bearing of the input rotational member; the lock sleeve is provided in a space between the high-low switching mechanism and the second output rotational member such that the lock sleeve is adjacent to the high-low sleeve as a different member; and the transmission mechanism includes
a first spring configured to bias the high-low sleeve and the lock sleeve such that the high-low sleeve and the lock sleeve are distanced from each other, and
a second spring configured to bias the lock sleeve such that the lock sleeve separates from the lock teeth.

7 . The power transmission device according to claim 6 , wherein:
the high-low sleeve meshes with the high-gear teeth on a side to be distanced from the lock sleeve; the high-low sleeve meshes with the low-gear teeth on a side to approach the lock sleeve; the lock sleeve meshes with the lock teeth at a position where the fork shaft meshes the high-low sleeve with the low-gear teeth; the clutch is placed around the shaft center of the first output rotational member on an opposite side to the high-low switching mechanism across the second output rotational member in a shaft-center direction of the first output rotational member such that the clutch is pressed by the pressing member moving toward the second output rotational member; the clutch is pressed by the pressing member at a position where the fork shaft meshes the high-low sleeve with the high-gear teeth, and the clutch is not pressed by the pressing member at a position where the fork shaft meshes the high-low sleeve with the low-gear teeth; the transmission mechanism includes a connecting mechanism configured to connect the rectilinearly-movable member to the fork shaft; and the connecting mechanism is configured to allow the rectilinearly-movable member to move between a position where the clutch is pressed by the pressing member and a position where the clutch is not pressed by the pressing member, still at the position where the fork shaft meshes the high-low sleeve with the high-gear teeth.

8 . The power transmission device according to claim 7 , wherein
the electronic control unit is configured to
i) perform the adjustment of the transmission torque of the clutch, by taking, as a reference point, a position where the clutch is pressed by the pressing member by a predetermined amount at a position where the high-low sleeve meshes with the high gear teeth, and
ii) perform the switching operation of the high-low switching mechanism based on the reference point and a moving dimension in design in the rectilinearly-movable member.

9 . The power transmission device according to claim 8 , wherein
the electronic control unit is configured to
i) apply a predetermined current to the motor and rotate the moto such that the pressing member presses the clutch,
ii) determine, as the reference point, one of a) a rotation angle at a time when the rotation of the motor stops, b) a rotation angle obtained by further rotating the motor by a predetermined reference angle from the rotation angle at a time when the rotation of the motor stops, and c) a rotation angle of the motor at a time when the current applied to the motor increases by a predetermined reference current,
iii) store a rotation angle of the motor which is obtained by rotating the motor relative to the reference po

Assignees

• Toyota Motor Co Ltd

Inventors

• Imafuku Mizuki
• Homan Akinori
• Arakawa Tomohiro

Classifications

• F16H2048/343

  using a rotary motor · CPC title

• F16H63/08

  Multiple final output mechanisms being moved by a single common final actuating mechanism · CPC title

• F16H48/34

  using electromagnetic or electric actuators · CPC title

• F16H48/24

  using positive clutches or brakes · CPC title

• F16H37/0806

  with a plurality of driving or driven shafts · CPC title