Abstract: In a driving force transmission apparatus, an oil inlet portion for introducing hydraulic fluid from one of spaces to the other one of the spaces is formed, and an apparatus case has an oil outlet portion for delivering the hydraulic fluid from the other one of the spaces to an outside of the other one of the spaces with an oil delivery capacity lower than an oil introducing capacity of the oil inlet portion. A pressure regulation valve for bringing the oil inlet portion into an open state upon reception of hydraulic pressure higher than or equal to a predetermined pressure from hydraulic fluid is arranged at the oil inlet portion.

Abstract: An ECU of a four wheel drive vehicle controls a transmission torque of a driving force transmission apparatus provided between a rear differential and a left rear wheel. The ECU includes a first computation unit that computes a command torque to be transmitted to the left rear wheel by the driving force transmission apparatus, based on a traveling state of the four wheel drive vehicle; and a second computation unit that corrects the command torque computed by the first computation unit, if a difference between rotation speeds of a pair of side gears of the rear differential is larger than or equal to a predetermined value.

Abstract: A driving force transmission apparatus including a tank which reserves lubricating oil in an accommodating space which is interposed between a housing and an inner shaft and an apparatus case which has a cylindrical accommodating portion which accommodates the housing, and in the case, the accommodating portion has an inner circumferential surface which faces an outer circumferential surface of the housing, and the tank has an oil inlet port which is opened to the inner circumferential surface of the accommodating portion and through which the lubricating oil in the accommodating space is let in based on a centrifugal force generated in association with the rotation of the housing when a four-wheel drive vehicle travels forwards in a two-wheel drive mode.

Abstract: A four-wheel drive vehicle includes: a driving force transmission system which transmits torque of a drive source to front wheels and rear wheels via gear mechanisms; a clutch provided in the driving force transmission system and capable of controlling an amount of the torque transmitted to the rear wheels; and a pressing mechanism which presses the clutch by transforming a part of the torque transmitted to the rear wheels into axial thrust. In the driving force transmission system, gear ratios of the gear mechanisms are set such that a direction of a differential rotation between a drive shaft connected to an input side of the clutch and a drive shaft connected to an output side of the clutch is not reversed even when a steered angle of the front wheels changes to a maximum value while the four-wheel drive vehicle is traveling forwards.

Abstract: A speed reduction mechanism includes a bearing mechanism arranged on an axis of an output mechanism and including ball bearings that are arranged in parallel with each other in an axial direction of a differential case. The differential case is rotatably supported by the ball bearings of the bearing mechanism such that the entirety of an outer periphery of one of the ball bearings faces an inner periphery of a first housing element that accommodates the differential case and that is made of a material having a stiffness lower than a stiffness of a material of a rotation force applying member, and the entirety of an outer periphery of the other one of the ball bearings faces an inner periphery of the rotation force applying member.

Abstract: When an outer ring is fitted to an inner periphery of an input member, which defines a center hole, and an inner ring is fitted to an eccentric portion with clearances in a reduction-transmission mechanism, in a state where tooth tips of the input member contact bottomlands of a rotation force applying member on a line perpendicular to a second axis and a fourth axis, a size between the second axis and a third axis is set to a size that is smaller than or equal to half of a size obtained by adding a diameter difference between an outside diameter of a ball bearing and an inside diameter of the input member, which defines the center hole, a diameter difference between an inside diameter of the ball bearing and an outside diameter of the eccentric portion and an operating clearance of the ball bearing.

Abstract: An electromagnetic clutch device includes: a meshing member; an electromagnetic coil; an armature; a cylindrical cam member; and a locking portion. The cam member is provided with a plurality of locked portions to be locked by the locking portion at different axial positions, such that the plurality of locked portions is formed adjacent to each other in a circumferential direction; the cam member rotates only by a first predetermined angle due to an axial movement of the armature from a first position to a second position, and the cam member further rotates only by a second predetermined angle due to a movement of the armature from the second position to the first position; and when locking of the locking portion is shifted from one of the plurality of locked portions to another locked portion circumferentially adjacent thereto so that the locking portion locks the another locked portion at a different axial position, the second meshing portion is meshed with the first meshing portion.

Abstract: A driving force transmission apparatus includes: a first cam mechanism that converts rotational force from a housing into first cam thrust force used as clutch force of a main clutch when the first cam mechanism is actuated through clutch action of a pilot clutch; and a second cam mechanism that is actuated prior to conversion of the rotational force into the first cam thrust force by the first cam mechanism, and that generates second cam thrust force for reducing an interval between clutch plates of the main clutch. The second cam mechanism includes an input cam member that rotates upon receiving rotational force used as actuating force of the input cam member from a cam actuating driving source, and an output cam member that generates the second cam thrust force between the output cam member and the input cam member and outputs the second cam thrust force.

Abstract: A clutch device includes; i) a clutch mechanism including a friction engagement member capable of rotating relative to a rotating member and a clutch member that is supplied with restoration force in a direction in which the clutch member departs from the friction engagement member by a restoration spring; and ii) a cam mechanism including; a cam member that is arranged in parallel to the clutch mechanism along a rotation axis line of the rotating member and that is incapable of rotating relative to the rotating member; and a cam follower capable of rolling on a cam surface that exists between the cam member and the clutch member. The cam angle is set to make torque applied to the clutch member due to reaction force accompanied by friction engagement with the friction engagement member larger than torque applied to the clutch member by thrust force caused by an activation of the cam mechanism.

Abstract: A driving force transmission apparatus including a tank which reserves lubricating oil in an accommodating space which is interposed between a housing and an inner shaft and an apparatus case which has a cylindrical accommodating portion which accommodates the housing, and in the case, the accommodating portion has an inner circumferential surface which faces an outer circumferential surface of the housing, and the tank has an oil inlet port which is opened to the inner circumferential surface of the accommodating portion and through which the lubricating oil in the accommodating space is let in based on a centrifugal force generated in association with the rotation of the housing when a four-wheel drive vehicle travels forwards in a two-wheel drive mode.

Abstract: A cage of each of ball bearings arranged on respective outer peripheries of eccentric portions of a motor shaft has an annular base portion interposed between an inner ring and an outer ring and a plurality of partition wall portions for forming pockets together with the base portion. In a first ball bearing, part of the base portion protrudes axially outward from the inner raceway and forms an oil receiving portion that receives lubricating oil from the second rolling bearing side, at a portion around the rotation axis and axially outward of the first rolling bearing.

Abstract: An ECU of a four wheel drive vehicle controls a transmission torque of a driving force transmission apparatus provided between a rear differential and a left rear wheel. The ECU includes a first computation unit that computes a command torque to be transmitted to the left rear wheel by the driving force transmission apparatus, based on a traveling state of the four wheel drive vehicle; and a second computation unit that corrects the command torque computed by the first computation unit, if a difference between rotation speeds of a pair of side gears of the rear differential is larger than or equal to a predetermined value.

Abstract: When a bearing includes outer and inner rings and the outer ring is fitted to the inner periphery of an input member, which defines a center hole, with a clearance and the inner ring is fitted to an eccentric portion with a clearance, a size between a second axis and a third axis is set to a size that is smaller than or equal to half of a size obtained by adding a diameter difference between an outside diameter of the bearing and an inside diameter of the input member, which defines the center hole, a diameter difference between an inside diameter of the bearing and an outside diameter of the eccentric portion and an operating clearance of the bearing in a state where the input member has been moved to contact the housing on a line perpendicular to the second axis and a fourth axis.

Abstract: In a reduction-transmission mechanism, a plurality of output members are arranged at such positions that a size that is the sum of a fitting clearance formed between an outer periphery of each output member and a corresponding one of needle roller bearings, a fitting clearance formed between the needle roller bearing and an inner periphery of an input member, which defines a corresponding one of a plurality of pin insertion holes, and a radial internal clearance in the needle roller bearing is smaller than a size that is the sum of a fitting clearance formed between a ball bearing and an outer periphery of an eccentric portion, a fitting clearance formed between the ball bearing and an inner periphery of the input member, which defines a center hole, and a radial internal clearance in the ball bearing.

Abstract: A motor driving force transmission system includes an electric motor that generates motor torque for actuating a differential mechanism portion and outputs the motor torque, and that has a motor shaft with eccentric portions, and a bearing mechanism including a ball bearing interposed between one-side axial end portion of a housing and one-side axial end portion of a differential case, a ball bearing interposed between the other-side axial end portion of the differential case and one-side axial end portion of the motor shaft, and a ball bearing interposed between the other-side axial end portion of the housing and the other-side axial end portion of the motor shaft. An axial load is applied to the ball bearings of the bearing mechanism by a spring.

Abstract: An electromagnetic clutch includes a rotating member; an electromagnetic coil that is arranged on a rotational axis of the rotating member and generates electro-magnetic force; an output mechanism that has an armature to which return force in a direction away from the electromagnetic coil is applied by a return spring; a cam mechanism that is juxtaposed along the rotational axis to the output mechanism, and has a control cam that is unable to rotate relative to the rotating member, and a cam follower that is able to roll between the control cam and the armature; and a relative rotation restricting device that is arranged on an axis of the cam mechanism, and that is configured to restrict relative rotation between the armature and the control cam when the electromagnetic coil is in a de-energized state.

Abstract: A speed reduction mechanism includes a bearing mechanism arranged on an axis of an output mechanism and including ball bearings that are arranged in parallel with each other in an axial direction of a differential case. The differential case is rotatably supported by the ball bearings of the bearing mechanism such that the entirety of an outer periphery of one of the ball bearings faces an inner periphery of a first housing element that accommodates the differential case and that is made of a material having a stiffness lower than a stiffness of a material of a rotation force applying member, and the entirety of an outer periphery of the other one of the ball bearings faces an inner periphery of the rotation force applying member.

Abstract: A motor driving force transmission device including a speed reduction and transmission mechanism which transmits a motor driving force to a rear differential, a first electric motor that is connected to the rear differential via the speed reduction and transmission mechanism and which produces a first motor driving force, a second electric motor that is connected to the first electric motor and the speed reduction and transmission mechanism and which produces a second motor driving force, and an ECU. The ECU outputs a control signal to drive both the first electric motor and the second electric motor when a driving torque required for the rear differential is equal to or larger than a predetermined torque, and outputs a control signal to drive alternately the first electric motor and the second electric motor when the driving torque required for the rear differential is smaller than the predetermined torque.

Abstract: A motor driving force transmission device includes electric motors which produce motor driving force with which a rear differential is operated and a speed reduction and transmission mechanism which reduces the speed of the motor driving force of the electric motors and transmits it to the rear differential. The speed reduction and transmission mechanism has eccentric cams which rotate as the electric motors are driven, transmission members which rotate as the eccentric cams rotate, and is disposed on an outer circumference of the rear differential.

Abstract: In a driving force transmission apparatus, an oil inlet portion for introducing hydraulic fluid from one of spaces to the other one of the spaces is formed, and an apparatus case has an oil outlet portion for delivering the hydraulic fluid from the other one of the spaces to an outside of the other one of the spaces with an oil delivery capacity lower than an oil introducing capacity of the oil inlet portion. A pressure regulation valve for bringing the oil inlet portion into an open state upon reception of hydraulic pressure higher than or equal to a predetermined pressure from hydraulic fluid is arranged at the oil inlet portion.