Differential device and method of adjusting differential device

A differential device has: a differential case supported so as to be rotatable with respect to a differential carrier fixed to the vehicle body; a differential gear mechanism composed of a plurality of pinion gears and side gears; pinion gear shafts that support the plurality of pinion gears; a tubular slide member that supports the pinion gear shafts in the differential case; an actuator that moves the slide member in the axial direction; and a position sensor that is attached to a sensor attachment member provided to the differential carrier and that is configured to detect an operating state of the actuator.

The disclosure of Japanese Patent Application No. 2017-148273 filed on Jul. 31, 2017 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a differential device including a differential mechanism that distributes an input drive force to a pair of output members while allowing differential motion, and to a method of adjusting the differential device.

2. Description of the Related Art

A differential device including a differential mechanism that distributes an input drive force to a pair of output members while allowing differential motion has hitherto been used to transfer a drive force of a drive source of a vehicle to right and left wheels, for example. In some of such differential devices, the operation state of the differential mechanism is switchable by an actuator. See Japanese Patent Application Publication No. 2005-240861 (JP 2005-240861 A), for example.

The differential device (differential motion restriction device) described in JP 2005-240861 A has a dog clutch that is capable of locking (restricting) differential motion between right and left side gears that serve as the pair of output members, and a linear electromagnetic solenoid that serves as the actuator which actuates the dog clutch. The dog clutch is constituted from a meshing gear portion formed on one of the side gears, and a meshing gear portion formed on a clutch piston supported so as to be movable in the rotational axis direction of the side gears with respect to a differential case. The linear electromagnetic solenoid has a yoke fixed to the differential case, a coil housed in the yoke, and a plunger provided so as to be movable in the rotational axis direction of the side gears by a magnetic force generated by energizing the coil.

When the coil is energized, a piston plate fixed to the clutch piston is pressed by the plunger, and the meshing gear portion of the clutch piston is meshed with the meshing gear portion of the one of the side gears to establish a differential lock state in which differential motion between the paired side gears is restricted. When the coil is de-energized, meanwhile, a return spring pushes back the clutch piston to cancel the differential lock state.

The differential device described in JP 2005-240861 A also has a position sensor (differential lock sensor) that is capable of detecting an operating state of the linear electromagnetic solenoid. The position sensor detects whether the linear electromagnetic solenoid is in a differential lock state or an unlocked state in accordance with the position of the piston plate, and is configured to have a sensor body fixed to a differential carrier and a position sensor portion that is movable with respect to the sensor body together with the piston plate.

In the differential device configured as described above, the position of the piston plate at which the position sensor is switched between the on state and the off state is affected by errors in the dimensions of the members of the differential device and errors in the assembly of such members. In the case where there is a significant error in the dimensions or the assembly, there may be caused a detection failure in which it cannot be accurately detected whether the linear electromagnetic solenoid is in a differential lock state or an unlocked state. In the case where such a detection failure is caused in the differential device described in JP 2005-240861 A, it is necessary to change the position of attachment of the sensor body through shim adjustment, for example. However, such adjustment work requires confirming the on/off state of the position sensor, and is troublesome.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a differential device that is configured to easy adjust the position of a position sensor that detects an operating state of an actuator, and a method of adjusting the differential device.

According to an aspect of the present invention, a differential device includes:

a differential mechanism that distributes an input drive force to a pair of output members while allowing differential motion;

a moving member that is configured to switch an operation state of the differential mechanism through advancing/retracting movement in an axial direction that is parallel to a rotational axis of the output members;

an actuator that moves the moving member in the axial direction;

a case member that houses the differential mechanism, the moving member, and the actuator; and

a position sensor that is attached to a sensor attachment portion provided to the case member and that is configured to detect an operating state of the actuator.

The position sensor has an insertion portion, a distal end portion of which is disposed inside the case member, and a flange portion disposed outside the case member.

The sensor attachment portion has a through hole through which the insertion portion of the position sensor is inserted in the axial direction.

The insertion portion is configured to turn about a central axis of the through hole in a state in which the flange portion is not fixed to the sensor attachment portion.

A position, in the axial direction, of the distal end portion of the insertion portion of the position sensor is varied in accordance with a position of fixation of the flange portion to the sensor attachment portion.

According to another aspect of the present invention, a method of adjusting the differential device includes fixing the flange portion to the sensor attachment portion at a position of the position sensor in the axial direction at a time when a signal state of the position sensor is switched when the position of the position sensor in the axial direction is varied.

With the differential device and the method of adjusting the differential device according to the aspects described above, it is possible to easily adjust the position of a position sensor that detects an operating state of an actuator.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1is a sectional view illustrating an example of the configuration of a differential device according to a first embodiment.FIG. 2is an exploded perspective view of the differential device.FIGS. 3A and 3Bare partial sectional views illustrating the differential device at the time when an actuator is not operating and when the actuator is operating, respectively.

A differential device1is used to distribute a drive force of a drive source such as an engine of a vehicle to a pair of output shafts (output members) while allowing differential motion. More specifically, the differential device1according to the present embodiment is mounted on a four-wheel-drive vehicle that includes a pair of right and left main drive wheels (e.g. front wheels) to which the drive force of the drive source is always transferred and a pair of right and left auxiliary drive wheels (e.g. rear wheels) to which the drive force of the drive source is transferred in accordance with the travel state. The differential device1is used as a differential device that distributes the drive force to the right and left auxiliary drive wheels. The vehicle is in a two-wheel-drive state in the case where the drive force is transferred to only the main drive wheels. The vehicle is in a four-wheel-drive state in the case where the drive force is transferred to the main drive wheels and the auxiliary drive wheels.

In the four-wheel-drive state, the differential device1distributes the input drive force to right and left drive shafts of the auxiliary drive wheels. In the two-wheel-drive state, meanwhile, the differential device1blocks transfer of the input drive force to the right and left drive shafts.

The differential device1has: a differential carrier10fixed to the vehicle body; a differential case2supported so as to be rotatable with respect to the differential carrier10via a pair of bearings11and12; a differential gear mechanism3composed of a plurality of pinion gears31and side gears32; pinion gear shafts4that support the pinion gears31; a tubular slide member5that supports the pinion gear shafts4in the differential case2; an actuator6that moves the slide member5in the axial direction which is parallel to a rotational axis O1of the differential case2; a pressing member7that receives and transfers a moving force of the actuator6to the slide member5; and a position sensor9that is attached to a sensor attachment member8provided to the differential carrier10and that is capable of detecting an operating state of the actuator6. The differential carrier10houses the differential gear mechanism3, the slide member5, and the actuator6.

The differential carrier10is an example of the case member according to the present invention. The differential gear mechanism3is an example of the differential mechanism according to the present invention. The slide member5is an example of the moving member according to the present invention.

Lubricating oil (differential oil) that lubricates the differential gear mechanism3is introduced into the differential case2. The differential gear mechanism3is disposed inside the slide member5. The actuator6is disposed outside the differential case2. A part of the pressing member7is inserted through a through hole211cformed in the differential case2. With this configuration, the actuator6moves the slide member5with respect to the differential case2in the axial direction via the pressing member7from the outside of the differential case2.

In the present embodiment, the slide member5supports two pinion gear shafts4, and each of the two pinion gear shafts4supports two pinion gears31. That is, in the present embodiment, the differential gear mechanism3is constituted by the four pinion gears31and a pair of side gears32meshed with the four pinion gears31with the gear axes of the pinion gears31and the side gears32orthogonal to each other. The pinion gears31and the side gears32have a plurality of gear teeth. InFIG. 2, however, such gear teeth are not illustrated.

As illustrated inFIG. 2, the pinion gear shafts4are each formed in a shaft shape as a whole, and both end portions of the pinion gear shafts4are inserted through two pinion gears31. The two pinion gear shafts4are fitted and meshed with each other at recessed portions40formed at the middle portions, in the axial direction, of the pinion gear shafts4. The two pinion gear shafts4are orthogonal to each other in the case where the pinion gear shafts4are seen along the rotational axis O1of the differential case2.

The slide member5has a tubular shape, the central axis of which coincides with the rotational axis O1of the differential case2, and is disposed so as to be movable in the axial direction with respect to the differential case2. The slide member5has: a cylindrical portion51formed in a cylindrical shape; a meshing portion52composed of a plurality of dog teeth (meshing teeth)52a; and an inner rib portion53provided on the radially inner side of the meshing portion52. The cylindrical portion51, the meshing portion52, and the inner rib portion53are integral with each other. A washer33is disposed between the inner peripheral surface of the cylindrical portion51of the slide member5and each pinion gear31.

The meshing portion52is formed on one side, in the axial direction, of the cylindrical portion51. The dog teeth52aproject in the axial direction. The cylindrical portion51has a plurality of long holes510that extend in the axial direction, that penetrate between the inner and outer peripheral surfaces of the cylindrical portion51, and that open toward the other side of the cylindrical portion51in the axial direction, which is the opposite side from the meshing portion52. In the present embodiment, the cylindrical portion51is provided with four long holes510. The long holes510are fitted with the pinion gear shafts4. Consequently, the slide member5is movable in the axial direction relative to the pinion gear shafts4, and rotatable together with the pinion gear shafts4.

When the slide member5receives a moving force of the actuator6to be moved in the axial direction, the meshing portion52is meshed with a meshed portion223(to be discussed later) of the differential case2in the circumferential direction. In this event, an axial end surface of the inner rib portion53abuts against a return spring14to receive the urging force of the return spring14.

The pressing member7has: a ring portion71disposed outside the differential case2; and a plurality of projecting pieces72provided to extend from the ring portion71in parallel with the rotational axis O1of the differential case2. In the present embodiment, the pressing member7is provided with four projecting pieces72. The pressing member7is formed by pressing a steel plate. The distal end portions (end portions remote from the base end portions gear the ring portion71) of the projecting pieces72are bent inward in the radial direction of the ring portion71. The pressing member7is rotated together with a first case member21to be discussed later.

A reinforcing ring13that suppresses deformation of the slide member5due to a torque reaction force from the pinion gear shafts4is disposed between the pressing member7and the slide member5. The reinforcing ring13is made of a steel material that is the same as that of the slide member5, for example, and formed in an L-shape in section.

The actuator6has: an annular electromagnet61that has a coil611and a molded resin portion612molded with the coil611embedded therein; a yoke62that serves as a magnetic path for magnetic flux of the electromagnet61generated by energizing the coil611; and an armature63that makes sliding contact with the molded resin portion612to be guided in the direction of the rotational axis O1of the differential case2. The section of the molded resin portion612taken along the rotational axis O1has a rectangular shape. The meshing portion52of the slide member5is meshed with the meshed portion223by a moving force of the actuator6transferred via the pressing member7and the reinforcing ring13.

The coil611of the electromagnet61generates magnetic flux when an excitation current is supplied from a controller101. The actuator6operates when an excitation current is supplied to the coil611. As illustrated inFIG. 2, the electromagnet61is provided with a boss portion613that projects from one end surface in the axial direction, and a wire614that supplies the excitation current to the coil611is led out from the boss portion613.

The yoke62is made of soft magnetic metal such as low-carbon steel, and has: a cylindrical portion621that covers the inner peripheral surface of the molded resin portion612from the inner side; and a rib portion622that projects outward from one end portion, in the axial direction, of the cylindrical portion621to cover one axial end surface of the molded resin portion612. The cylindrical portion621and the rib portion622are integral with each other.

A rotation prevention member64and a stopper ring65are disposed at an end portion of the cylindrical portion621of the yoke62on the opposite side from the rib portion622. The rotation prevention member64is engaged with the yoke62so as not to be relatively rotatable. The stopper ring65retains the electromagnet61and the rotation prevention member64on the yoke62. The rotation prevention member64is made of non-magnetic metal such as austenitic stainless steel, and has: an annular portion641disposed at the outer periphery of the cylindrical portion621of the yoke62; and a pair of protruding portions642provided at two locations in the circumferential direction to project in the axial direction from the annular portion641. The annular portion641and the protruding portions642are integral with each other.

The rotation prevention member64prevents rotation of the yoke62with the protruding portions642engaged with recessed portions100formed in the differential carrier10, and restricts axial movement of the yoke62. The protruding portions642of the rotation prevention member64are inserted through insertion through holes632aformed in the armature63to extend in the axial direction to prevent rotation of the armature63with respect to the yoke62and the differential carrier10. The protruding portions642each have: a plate portion642ain a flat plate shape inserted through the insertion through hole632aof the armature63; and a retention protrusion642bdisposed closer to the recessed portion100of the differential carrier10than the insertion through bole632ato restrict axial movement of the armature63with respect to the yoke62. In the present embodiment, the retention protrusion642bis formed by cutting and raising a part of the plate portion642a.

The stopper ring65is disposed at a position at which the annular portion641of the rotation prevention member64is interposed between the electromagnet61and the stopper ring65, and fixed to the cylindrical portion621of the yoke62by welding, for example. The stopper ring65and the annular portion641of the rotation prevention member64have notches65aand641a, respectively, with which the boss portion613which is provided on the molded resin portion612of the electromagnet61is fitted.

The armature63is made of soft magnetic metal such as low-carbon steel, and has: an outer annular portion631disposed at the outer periphery of the electromagnet61; a side plate portion632formed so as to project inward from one end portion, in the axial direction, of the outer annular portion631; and a flange portion633formed so as to project outward from the other end portion, in the axial direction, of the outer annular portion631. The outer annular portion631, the side plate portion632, and the flange portion633are integral with each other.

The side plate portion632of the armature63has: two insertion through holes632a, through which the respective protruding portions642of the rotation prevention member64are inserted; a through hole632bpenetrated by the boss portion613of the electromagnet61; and a plurality of (ten in the example illustrated inFIG. 2) oil holes632cthat allow a flow of lubricating oil.

A detected plate66to be detected by the position sensor9is attached to the side plate portion632of the armature63. The detected plate66is fixed to the side plate portion632by two bolts601. The two bolts601are inserted through two bolt holes632d(illustrated inFIG. 2) formed in the side plate portion632and two through holes66bformed in the detected plate66.

The detected plate66is made of a magnetic material such as iron, has a plate shape, and has a detected surface66athat faces a detection surface91aof the position sensor9. The detected surface66ais perpendicular to the rotational axis O1. A predetermined gap is provided between the detection surface91aof the position sensor9and the detected surface66a.

The differential case2has a first case member21in a disc shape and a second case member22in a bottomed cylindrical shape. The first case member21blocks the opening of the second case member22. A washer34in an annular plate shape is disposed in the differential gear mechanism3between the pair of side gears32and the first case member21and between the pair of side gears32and the second case member22.

The second case member22has: a cylindrical portion221that houses the differential gear mechanism3and the slide member5therein; a bottom portion222that extends inward from one end portion, in the axial direction, of the cylindrical portion221; the meshed portion223with which the meshing portion52of the slide member5is meshed; and a flange portion224that extends outward from the other end portion, in the axial direction, of the cylindrical portion221. The cylindrical portion221, the bottom portion222, the meshed portion223, and the flange portion224are integral with each other.

The cylindrical portion221has a plurality of oil holes221athat allow a flow of lubricating oil. The bottom portion222has: a shaft insertion hole222a, into which a drive shalt coupled to one of the side gears32so as not to be relatively rotatable is inserted; and an annular groove222bthat houses the return spring14. In the present embodiment, the return spring14is constituted of a wave washer, and housed in the annular groove222bas compressed in the axial direction. The meshed portion223is composed of multiple dog teeth223aprovided at equal intervals along the circumferential direction, and provided gear the bottom portion222of the second case member22. The return spring14urges the slide member5in the direction of moving the slide member5away from the bottom portion222of the second case member22.

The first case member21has: a cylindrical portion211opposed to the bottom portion222of the second case member22in the axial direction; and a flange portion212brought into abutment with the flange portion224of the second case member22. The cylindrical portion211and the flange portion212are integral with each other.

The flange portion212of the first case member21and the flange portion224of the second case member22are coupled to each other by a plurality of screws20(seeFIG. 2). The cylindrical portion211has a shaft insertion hole211a, into which a drive shaft coupled to the other of the side gears32so as not to be relatively rotatable is inserted.

A drive force is input to the differential case2from an annular ring gear23(seeFIG. 1) fixed to the flange portions212and224of the first and second case members21and22, respectively. The ring gear23is fixed to a portion of the outer periphery of the cylindrical portion221of the second case member22, which is gear the flange portion224. The ring gear23is fixed by a plurality of fastening bolts24so as to rotate together with the differential case2.

The position sensor9is a non-contact magnetic sensor that magnetically detects the position, in the axial direction, of the armature63and the detected plate66, and outputs an electric signal that matches variations in the magnetic flux density to the controller101via a wire103. The position sensor9is set such that the signal state of the position sensor9is switched on and off in accordance with the distance between the detection surface91aof the position sensor9and the detected surface66aof the detected plate66.

As illustrated inFIG. 3, the position sensor9has: an insertion portion91, the distal end portion of which is disposed inside the differential carrier10; a flange portion92disposed outside the differential carrier10; and an operation portion93disposed on the opposite side of the flange portion92from the insertion portion91. The flange portion92of the position sensor9is fixed to the sensor attachment member8by a bolt900. The sensor attachment member8is an example of the sensor attachment portion according to the present invention.

The distal end surface, in the axial direction, of the insertion portion91of the position sensor9is formed as the detection surface91awhich detects magnetic flux that snatches the distance, in the axial direction, from the detected plate66.

The position sensor9is fixed to the differential carrier10via the sensor attachment member8which is attached to the differential carrier10. The sensor attachment member8has: a body portion81interposed between the differential carrier10and the flange portion92of the position sensor9; and a cylindrical portion82inserted through an attachment hole102formed in the differential carrier10. The sensor attachment member8has a through hole810that allows the insertion portion91of the position sensor9to be inserted therethrough in the axial direction. The position sensor9is turnable about the central axis of the through hole810in a state in which the flange portion92is not fixed to the sensor attachment member8.

An annular groove91b, in which an O-ring901is disposed, is formed in an outer peripheral surface91cof the insertion portion91that faces an inner peripheral surface810a(seeFIGS. 3 and 4to be discussed later) of the through hole810in the sensor attachment member8. Consequently, a space between the position sensor9and the sensor attachment member8is sealed.

Next, operation of the differential device1will be described with reference toFIGS. 3A and 3B. The differential device1is switched between a coupled state and a non-coupled state in accordance with whether the actuator6is operating or is not operating. In the coupled state, the slide member5and the differential case2are coupled so as not to be rotatable relative to each other with the dog teeth52aof the meshing portion52and the dog teeth223aof the meshed portion223meshed with each other in the circumferential direction. In the non-coupled state, the slide member5and the differential case2are rotatable relative to each other.

When the actuator6is not operating with no excitation current supplied to the coil611of the electromagnet61, the slide member5is moved toward the cylindrical portion211of the first case member21by the restoring force of the return spring14, which releases meshing between the meshing portion52of the slide member5and the meshed portion223of the differential case2. When the electromagnet61is de-energized, the armature63is returned to a position, at which the armature63is away from the bottom portion222, by the restoring force of the return spring14which is transferred via the slide member5, the reinforcing ring13, and the pressing member7.

When the actuator6is not operating, the differential case2and the slide member5are rotatable relative to each other, and thus transfer of a drive force from the differential case2to the differential gear mechanism3is blocked. Consequently, the vehicle is brought into the two-wheel-drive state with the drive force which is input from the ring gear23to the differential case2not transferred to the drive shafts.

When an excitation current is supplied to the coil611of the electromagnet61, on the other hand, magnetic flux is generated in a magnetic path G indicated by the dashed line inFIG. 3B. The armature63then is moved toward the second case member22in the axial direction by the magnetic force of the electromagnet61. Consequently, the pressing member7presses the slide member5toward the bottom portion222of the second case member22via the reinforcing ring13, which moves the slide member5to a position at which the meshing portion52and the meshed portion223are meshed with each other. The position of the armature63is detected by the position sensor9which is fixed to the differential carrier10.

When the meshing portion52and the meshed portion223are meshed with each other, the vehicle is brought into the four-wheel-drive state with the drive force which is input from the ring gear23to the second case member22of the differential case2transferred to the drive shafts via the slide member5, the pinion gear shafts4of the differential gear mechanism3, the four pinion gears31, and the side gears32.

When the actuator6is brought from the non-operating state into the operating state, the controller101supplies the electromagnet61with an excitation current with a large current value that enables rapid movement of the slide member5. After that, when it is determined on the basis of an output signal from the position sensor9that the meshing portion52and the meshed portion223are meshed with each other, the current value of the excitation current is reduced to a relatively small current value that can still maintain the state in which the meshing portion52and the meshed portion223are meshed with each other. Consequently, power consumption can be reduced.

Next, the sensor attachment member8and the position sensor9will be described in detail with reference toFIGS. 4 to 6B.FIG. 4is a perspective view illustrating an example of the configuration of the sensor attachment member8and the position sensor9.FIGS. 5A and 5Bare a plan view and a side view, respectively, illustrating an example of the configuration of the sensor attachment member8and the position sensor9, illustrating a state in which the position sensor9is turned to one side of the sensor attachment member8.FIGS. 6A and 6Bare a plan view and a side view, respectively, illustrating an example of the configuration of the sensor attachment member8and the position sensor9, illustrating a state in which the position sensor9is turned to the other side of the sensor attachment member8.

The sensor attachment member8has the body portion81in a plate shape and the cylindrical portion82in a cylindrical shape. The body portion81and the cylindrical portion82are integral with each other. An opening end surface81aof the body portion81, which is around the opening of the through hole810and is adjacent to the flange portion92, is a flat surface that extends along a direction that is orthogonal to the axial direction of the insertion portion91of the position sensor9. The opening end surface81afaces the flange portion92of the position sensor9. The cylindrical portion82is provided so as to project from an end surface81bof the body portion81on the opposite side from the opening end surface81a. The flange portion92of the position sensor9has an insertion through hole92athrough which the bolt900is inserted.

The body portion81has a long hole811that extends arcuately about a central axis O2of the through hole810. The body portion81also has two insertion through holes801and802through which bolts (not illustrated) are inserted for fixation to the differential carrier10. The flange portion92is fixed to the sensor attachment member8by the bolt900which serves as a fixing member in a shaft shape inserted through the long hole811. The fixing member may be a rivet, for example, rather than a bolt.

The opening end surface of the long hole811the body portion81is an inclined surface81cinclined at a predetermined angle with respect to the circumferential direction about the central axis O2of the through hole810. The insertion portion91of the position sensor9is turnable in a predetermined angular range about the central axis O2of the through hole810in a state in which the flange portion92is not fixed to the sensor attachment member8, and the flange portion92is fixed to the inclined surface81cof the body portion81at any position in the circumferential direction about the central axis O2. The flange portion92has: a rotary end921that is rotated when the insertion portion91is turned; and a moving end922that is moved along the long hole811when the insertion portion91is turned. The predetermined angular range refers to an angle that matches the distance over which the moving end922of the flange portion92is moved between one end811aand the other end811bin the circumferential direction of the long hole811.

When the insertion portion91is turned about the central axis O2of the through hole810in a state in which the position sensor9is not fixed to the sensor attachment member8, the position of the position sensor9in the axial direction is varied in accordance with the inclined surface81c. More specifically, when the amount of projection of the insertion portion91from an axial end surface82aof the cylindrical portion82of the sensor attachment member8at the time when the moving end922of the flange portion92of the position sensor9is positioned at the one end811aof the long hole811is defined as D1, and when the amount of projection of the insertion portion91from the axial end surface82aof the cylindrical portion82of the sensor attachment member8at the time when the moving end922of the flange portion92of the position sensor9is positioned at the other end811bof the long hole811is defined as D2, the amount of projection D1is larger than the amount of projection D2(D1>D2). That is, the position, in the axial direction, of the distal end portion of the insertion portion91of the position sensor9is varied in accordance with the position of fixation of the flange portion92to the sensor attachment member8.

Thus, a margin for adjustment of the amount of projection of the insertion portion91from the sensor attachment member8is varied in accordance with the inclination angle of the inclined surface81cof the sensor attachment member8. That is, a distance d (D1−D2) over which adjustment can be made in the axial direction of the position sensor9is increased as the inclination angle of the inclined surface81cis larger, and the distance d (D1−D2) over which adjustment can be made in the axial direction of the position sensor9is reduced as the inclination angle of the inclined surface81cis smaller. The inclination angle of the inclined surface81cis set to such an angle that the detection surface91aof the insertion portion91does not contact the detected surface66aof the detected plate66when the moving end922of the flange portion92is moved from the one end811aof the long hole811to the other end811b.

A washer800, through which the bolt900is inserted, is disposed between the flange portion92of the position sensor9and the sensor attachment member8. An end surface800aof the washer800adjacent to the sensor attachment member8in the axial direction is an inclined surface that extends along the inclined surface81c. When the insertion portion91of the position sensor9is rotated, the washer800is moved together with the moving end922of the flange portion92to be slid on the inclined surface81cof the sensor attachment member8.

When the moving end922of the flange portion92is moved between the one end811aand the other end811bof the long hole811, a central axis O3of the bolt900is moved so as to draw an arcuate locus with a radius R (the distance between the central axis O2of the through hole810and the central axis O3of the bolt900). In this way, the flange portion92can be fixed to the sensor attachment member8at different positions at which the flange portion92is equidistant from the central axis O2of the through hole810.

Next, a method of adjusting the position of the position sensor9in the axial direction will be described with reference toFIGS. 7A to 7C.FIGS. 7A, 7B, and 7Cillustrate an example of a process for position adjustment of the position sensor9.FIG. 7Aillustrates a preparation process for position adjustment of the position sensor9.FIG. 7Billustrates an intermediate process.FIG. 7Cillustrates a fixing process in which the position sensor9is fixed to the sensor attachment member8after the position adjustment is completed. The differential device1is in a coupled state in all the processes illustratedFIGS. 7A, 7B, and 7C.

First, as illustrated inFIG. 7A, an excitation current is supplied to the electromagnet61to establish a coupled state in which the dog teeth52aof the meshing portion52and the dog teeth223aof the meshed portion223are meshed with each other in the circumferential direction. The moving end922of the flange portion92of the position sensor9is disposed at the one end811aof the long hole811. That is, in the preparation process, the position sensor9is located closest to the detected plate66with the differential device1in the coupled state. In this event, the position sensor9outputs an electric signal for the on state to the controller101. The distance, in the axial direction, between the detection surface91aof the position sensor9and the detected surface66aof the detected plate66is defined as S1.

FIG. 7Billustrates a state in which the insertion portion91of the position sensor9is turned by a predetermined angle about the central axis O2so that the detection surface91aof the insertion portion91of the position sensor9is moved in the direction away from the detected surface66aof the detected plate66. In this state, a distance S2, in the axial direction, between the detection surface91aof the position sensor9and the detected surface66aof the detected plate66is longer than the distance S1, but an electric signal for the on state is still output from the position sensor9.

FIG. 7Cillustrates a state in which the insertion portion91of the position sensor9is further turned, so that a distance S3between the detection surface91aof the insertion portion91and the detected surface66aof the detected plate66is further longer and the electric signal which is output from the position sensor9is switched from the on state to the off state. When the signal state of the position sensor9is switched from the on state to the off state in this manner, turning of the insertion portion91of the position sensor9is stopped, and the position sensor9is fixed to the sensor attachment member8by fastening the bolt900to a nut902. Consequently, the fixing process in the process of adjusting the position sensor9is completed. In this way, the position of the position sensor9at the time when the signal state of the position sensor9is switched is determined as the position of fixation.

As described above, in adjusting the position of the position sensor9in the axial direction, the position of the position sensor9in the axial direction is decided on the basis of the signal state of the position sensor9at the time when the distance between the detected plate66and the position sensor9is varied while the differential device1is maintained in the coupled state.

According to the first embodiment described above, the following functions and effects can be obtained.

(1) With the present embodiment, the insertion portion91is turnable in the through hole810, and the flange portion92can be fixed to the sensor attachment member8at different positions at which the flange portion92is equidistant from the central axis O2of the through hole810, in a state in which the position sensor9is not fixed to the sensor attachment member8. The position of the position sensor9in the axial direction is varied by turning the insertion portion91. Thus, the position of the position sensor9can be adjusted easily compared to a case where the position of the position sensor is adjusted through shim adjustment as in the differential device described in JP 2005-240861 A, for example.

(2) The sensor attachment member8has the long hole811which extends arcuately about the central axis O2of the through hole810. The flange portion92is fixed to the sensor attachment member8by the bolt900in a shaft shape which is inserted through the long hole811. That is, it is only necessary to fasten the bolt900in order to fix the position sensor9to the sensor attachment member8. That is, the position sensor9can be fixed to the sensor attachment member8easily after the position of the position sensor9is adjusted.

(3) The sensor attachment member8has the inclined surface81cwhich is inclined at a predetermined angle with respect to the circumferential direction about the central axis O2of the through hole810. The flange portion92of the position sensor9is fixed to the inclined surface81cat any position in the circumferential direction. With this configuration, the position of the position sensor9in the axial direction can be varied by just turning the insertion portion91when the position of the position sensor9in the axial direction is adjusted. That is, the position of the position sensor9in the axial direction can be adjusted with a simple configuration without separately providing a part for adjusting the position of the position sensor9in the axial direction.

Next, a modification of the differential device1according to the first embodiment will be described with reference toFIGS. 8 to 10B.FIG. 8is a perspective view illustrating an example of the configuration of a sensor attachment member8A according to the modification.FIGS. 9A and 9Bare a plan view and a side view, respectively, illustrating an example of the configuration of the sensor attachment member8A and the position sensor9according to the modification, illustrating a state in which the position sensor9is turned to an end portion an one side of the sensor attachment member8A.FIGS. 10A and 10Bare a plan view and a side view, respectively, illustrating an example of the configuration of the sensor attachment member8A and the position sensor9according to the modification, illustrating a state in which the position sensor9is turned to a middle position between the end portion on the one side and an end portion on the other side of the sensor attachment member8A.FIGS. 11A and 11Bare a plan view and a side view, respectively, illustrating an example of the configuration of the sensor attachment member8A and the position sensor9according to the modification, illustrating a state in which the position sensor9is turned to the end portion on the other side of the sensor attachment member8A.

The present modification differs from the first embodiment in the configuration of the sensor attachment member8A. That is, while the sensor attachment member8according to the first embodiment has the inclined surface81c, the sensor attachment member8A according to the modification has a plurality of stepped surfaces in place of the inclined surface81c.

As with the sensor attachment member8according to the first embodiment, the sensor attachment member8A according to the modification has the body portion81and the cylindrical portion82which are integral with each other. The opening end surface81aof the body portion81is a flat surface that is orthogonal to the central axis O2of the through hole810. The washer800, through which the bolt900is inserted, is disposed between the flange portion92of the position sensor9and the sensor attachment member8A. Both end surfaces, in the axial direction, of the washer800are parallel to the opening end surface81aof the body portion81.

The body portion81has first and second stepped surfaces81dand81ein a staircase shape at different positions in the direction of the rotational axis O1. Of the opening end surface81aof the body portion81, a surface that is adjacent to the first stepped surface81dalong the direction of arrangement of the first and second stepped surfaces81dand81eis defined as a reference surface81f. The reference surface81fis continuous with the opening end surface81awith no step therebetween.

The first and second stepped surfaces81dand81eare parallel to the reference surface81fof the body portion81. When a direction that is parallel to the central axis O2of the through hole810and away from the cylindrical portion82is defined as the height direction, the first stepped surface81dis formed to be higher in position in the axial direction than the reference surface81fof the body portion81, and the second stepped surface81eis formed to be higher in position in the axial direction than the first stepped surface81d. With this configuration, the position of the position sensor9in the axial direction can be varied in accordance with the height of the first and second stepped surfaces81dand81ein the axial direction.

More specifically, when the amount of projection of the insertion portion91from the axial end surface82aof the cylindrical portion82of the sensor attachment member8A at the time when the moving end922of the flange portion92of the position sensor9is positioned on the reference surface81fis defined as E1, the amount of projection of the insertion portion91from the axial end surface82aof the cylindrical portion82of the sensor attachment member8A at the time when the moving end922of the flange portion92of the position sensor9is positioned on the first stepped surface81dis defined as E2, and the amount of projection of the insertion portion91from the axial end surface82aof the cylindrical portion82of the sensor attachment member8A at the time when the moving end922of the flange portion92of the position sensor9is positioned on the second stepped surface81eis defined as E3, the amount of projection E1is larger than the amount of projection E2, and the amount of projection E2is larger than the amount of projection E3(E1>E2>E3). That is, the position, in the axial direction, of the distal end portion of the insertion portion91of the position sensor9is varied stepwise in accordance with the position of fixation of the flange portion92to the sensor attachment member8A. In this way, the flange portion92of the position sensor9is fixed to any of the reference surface81fand the first and second stepped surfaces81dand81e.

According to the present modification, the same functions and effects as those according to the first embodiment can be obtained. In the present modification, the sensor attachment member8A has the reference surface81fand the first and second stepped surfaces81dand81ein a staircase shape at different positions in the axial direction, and the flange portion92is fixed to any of the reference surface81fand the first and second stepped surfaces81dand81e. Thus, the position sensor9can be stably fixed to the sensor attachment member8A.

Next, a differential device according to a second embodiment will be described with reference toFIGS. 12 to 13B.FIG. 12is a sectional view illustrating an example of the configuration of the differential device according to the second embodiment.FIGS. 13A and 13Bare partial sectional views illustrating the differential device according to the second embodiment at the time when an actuator is not operating and when the actuator is operating, respectively.

A differential device1A includes: a differential carrier10fixed to the vehicle body; a differential case2rotatably supported by the differential carrier10; a first side gear35and a second side gear36housed in the differential case2; a plurality of pinion gear sets that include first pinion gears41and second pinion gears42meshed with each other; an engagement/disengagement member50that is capable of allowing and blocking transfer of a drive force between the differential case2and the first side gear35; an actuator6that moves the engagement/disengagement member5; and a position sensor9that is attached to a sensor attachment member8that serves as a sensor attachment portion provided to the differential carrier10and that is capable of detecting an operating state of the actuator6. The configuration of the sensor attachment member8and the position sensor9is the same as that according to the first embodiment.

The actuator6is controlled by the controller101, and allows and blocks coupling between the differential case2and the first side gear35through movement of the engagement/disengagement member50. When the differential case2and the first side gear35are coupled to each other by the engagement/disengagement member50, the differential case2and the first side gear35are rotated together with each other. When the differential case2and the first side gear35are decoupled from each other, rotation of the first side gear35relative to the differential case2is allowed.

The first side gear35and the second side gear36have a tubular shape. A spline fitting portion350, to which one of the output shafts is coupled so as not to be relatively rotatable, is formed in the inner peripheral surface of the first side gear35. A spline fitting portion360, to which the other output shall is coupled so as not to be relatively rotatable, is formed in the inner peripheral surface of the second side gear36.

The differential case2is supported so as to be rotatable with respect to the differential carrier10, which is fixed to the vehicle body, via a pair of bearings105and106. As illustrated inFIG. 12, the differential carrier10is provided with an attachment hole100afor attachment of the position sensor9which outputs an electric signal that indicates the operation state of the actuator6.

The differential case2, the first side gear35, and the second side gear36are disposed so as to be rotatable relative to each other about the common rotational axis O1. Hereinafter, the direction which is parallel to the rotational axis O1will be referred to as the “axial direction”. The engagement/disengagement member50is pressed by the actuator6to be moved in the axial direction.

The differential case2has a plurality of holding holes200that rotatably hold the first pinion gears41and the second pinion gears42. The first pinion gears41and the second pinion gears42are revolvable about the rotational axis O1, and rotatable in the holding holes200with their central axes serving as rotational axes.

The first side gear35and the second side gear36have the same outside diameter. Gear portions351and361that include a plurality of helical teeth are formed on the respective outer peripheral surfaces of the first side gear35and the second side gear36. A center washer121is disposed between the first side gear35and the second side gear36. A first side washer122is disposed at a side of the first side gear35. A second side washer123is disposed at a side of the second side gear36.

The first pinion gears41each have a long gear portion411, a short gear portion412, and a coupling portion413that couples the long gear portion411and the short gear portion412to each other in the axial direction. The long gear portion411, the short gear portion412, and the coupling portion413are integral with each other. Similarly, the second pinion gears42each have a long gear portion421, a short gear portion422, and a coupling portion423that couples the long gear portion421and the short gear portion422to each other in the axial direction. The long gear portion421, the short gear portion422, and the coupling portion423are integral with each other.

The long gear portion411of the first pinion gear41is meshed with the gear portion351of the first side gear35and the short gear portion422of the second pinion gear42. The short gear portion412of the first pinion gear41is meshed with the long gear portion421of the second pinion gear42. The long gear portion421of the second pinion gear42is meshed with the gear portion361of the second side gear36and the short gear portion412of the first pinion gear41. The short gear portion422of the second pinion gear42is meshed with the long gear portion411of the first pinion gear41.

In the case where the first side gear35and the second side gear36are rotated at the same speed as each other, the first pinion gears41and the second pinion gears42revolve together with the differential case2without rotating in the holding holes200. When the rotational speeds of the first side gear35and the second side gear36are different from each other such as during a turn of the vehicle, for example, the first pinion gears41and the second pinion gears42revolve while rotating in the holding holes200. Consequently, a drive force input to the differential case2is distributed to the first side gear35and the second side gear36while differential motion is allowed. The first side gear35, the second side gear36, and the first and second pinion gears41and42correspond to the differential mechanism according to the present invention.

The engagement/disengagement member50is movable in the axial direction between a coupled position, at which the engagement/disengagement member50couples the differential case2and the first side gear35to each other so as not to be relatively rotatable, and a non-coupled position, at which the engagement/disengagement member50allows relative rotation between the differential case2and the first side gear35.

The engagement/disengagement member50has: an annular portion510disposed inside the differential case2; and a plurality of leg portions520that project from an axial end surface of the annular portion510to be inserted through insertion through holes202formed in the differential case2. The annular portion510and the leg portions520are integral with each other. Rotation of the engagement/disengagement member50relative to the differential case2is restricted, and the engagement/disengagement member50is movable in the axial direction with respect to the differential case2. The annular portion510of the engagement/disengagement member50includes a plurality of meshing teeth510athat project in the axial direction.FIG. 13Aillustrates a state in which the engagement/disengagement member50is located at the non-coupled position.FIG. 13Billustrates a state in which the engagement/disengagement member50is located at the coupled position. The engagement/disengagement member50corresponds to the moving member according to the present invention.

When the engagement/disengagement member50is located at the coupled position, differential motion between the differential case2and the first side gear35is restricted to make the first pinion gears41and the second pinion gears42non-rotatable, and differential motion between the differential case2and the second side gear36is also restricted. The engagement/disengagement member50is urged toward the non-coupled position by a return spring18disposed between the first side gear35and the engagement/disengagement member50.

The actuator6has: an electromagnet61in a circular ring shape that has a coil611that generates magnetic flux through energization; a yoke62that constitutes a part of a magnetic path G (seeFIG. 13B) for magnetic flux of the electromagnet61; an armature63made of a soft magnetic body that constitutes the magnetic path G together with the yoke62and that is moved in the axial direction together with the engagement/disengagement member50; a transfer member70that transfers a moving force of the armature63to the engagement/disengagement member50; a non-magnetic ring67interposed between the electromagnet61and the yoke62; and a rotation prevention member68that is engageable so as not to be rotatable relative to the yoke62.

The electromagnet61has: the coil611which is formed by winding an enameled wire; and the molded resin portion612which is molded with the coil611embedded therein. The yoke62has: the cylindrical portion621which is inserted through the inside of the electromagnet61; and the rib portion622which bulges radially outward from one end portion, in the axial direction, of the cylindrical portion621. The cylindrical portion621and the rib portion622are integral with each other. A plate17that restricts axial movement of the yoke62with respect to the differential case2is provided on the inner peripheral side of the cylindrical portion621.

The armature63has: the outer annular portion631in a cylindrical shape; and the side plate portion632which is formed so as to extend radially inward from one end portion, in the axial direction, of the outer annular portion631. The outer annular portion631and the side plate portion632are integral with each other. The transfer member70abuts against an end portion, on the inner peripheral side, of the side plate portion632. An end surface632eof the side plate portion632on the opposite side from the outer annular portion631in the axial direction faces the detection surface91aof the position sensor9. The end surface632eof the armature63is formed as a detected surface to be detected by the position sensor9.

The transfer member70is formed by pressing a plate material made of non-magnetic metal such as austenitic stainless steel, for example, and has: a ring-shaped annular portion701that abuts against the side plate portion632of the armature63; three extension portions702that extend in the axial direction from the annular portion701; and fixed portions703that project inward from the distal end portions of the extension portions702to be fixed to the engagement/disengagement member50. The annular portion701, the extension portions702, and the fixed portions703are integral with each other. The annular portion701of the transfer member70is slid over the side plate portion632of the armature63to be rotated together with the differential case2. The fixed portions703have insertion through holes703afor insertion of press-fitting pins19for fixation to the engagement/disengagement member50. The engagement/disengagement member50has insertion through holes530for insertion of the press-fitting pins19.

The differential case2has a first case member25and a second case member26which are fixed to each other by a plurality of screws201. The first case member25has: a cylindrical portion251in a cylindrical shape that rotatably holds the pinion gear sets; a bottom portion252that extends inward from one end portion of the cylindrical portion251; and a flange portion253that abuts against the second case member26. The cylindrical portion251, the bottom portion252, and the flange portion253are integral with each other. An annular recessed portion250, in which the electromagnet61and the yoke62are disposed, is formed at the angle portion between the cylindrical portion251and the bottom portion252.

The first side gear35and the second side gear36are disposed on the inner side of the cylindrical portion251. The first case member25is made of metal with lower magnetic permeability than that of the yoke62. A ring gear (not illustrated) is fixed to the flange portion253. The differential case2is rotated about the rotational axis O1by a drive force transmitted to the ring gear.

When an excitation current is supplied to the electromagnet61, magnetic flux is generated in the magnetic path G illustrated inFIG. 13B, and the side plate portion632of the armature63is attracted toward the rib portion622of the yoke62. Consequently, the armature63is moved in the axial direction. The axial movement of the armature63moves the engagement/disengagement member50, which is coupled to the armature63by the transfer member70, in the axial direction.

A plurality of meshing teeth353, with which the meshing teeth510aof the engagement/disengagement member50are meshed, is formed on an annular wall portion352of the first side gear35. The annular wall portion352is provided so as to project toward the outer peripheral side with respect to the gear portion351.

When the engagement/disengagement member50is pressed by the armature63via the transfer member70to be moved to the coupled position, the meshing teeth510aare meshed with the meshing teeth353of the first side gear35. Consequently, the engagement/disengagement member50and the first side gear35are coupled so as not to be relatively rotatable. When the engagement/disengagement member50is moved to the non-coupled position by the urging force of the return spring18, on the other hand, the meshing teeth510aand353are not meshed with each other, and the engagement/disengagement member50and the first side gear35are relatively rotatable.

A spherical body27is disposed between the bottom portion252of the first case member25and the engagement/disengagement member50. The spherical body27is held by the first case member25such that a part of the spherical body27is housed in a dent in the axial direction provided in the bottom portion252. The first case member25and the engagement/disengagement member50generate a thrust in the axial direction that moves the engagement/disengagement member50away from the bottom portion252using a cam action via the spherical body27.

The rotation prevention member68has: an annular body portion681externally fitted to the cylindrical portion621of the yoke62; a pair of protruding portions682provided at two locations in the circumferential direction to project in the axial direction from the body portion681; and projecting pieces683provided to the protruding portions682to serve as retention portions that retain the side plate portion632of the armature63. The body portion681, the protruding portions682, and the projecting pieces683are integral with each other. The rotation prevention member68is prevented from rotating with respect to the differential carrier10with parts of the protruding portions682on the distal end side engaged with engagement portions100bprovided to the differential carrier10.

In a state in which the meshing teeth510aof the engagement/disengagement member50and the meshing teeth353of the first side gear35meshed with each other, relative rotation between the differential case2and the first side gear35is restricted, and a drive force is transferred from the differential case2to the first side gear35is the engagement/disengagement member50. The first pinion gears41and the second pinion gears42are not rotatable, and differential motion between the differential case2and the second side gear36is also restricted. Consequently, differential motion between the first side gear35and the second side gear36is restricted. In a state in which the meshing teeth510aof the engagement/disengagement member50are not meshed with the meshing teeth353of the first side gear35, on the other hand, a drive force input to the differential case2is distributed to the first side gear35and the second side gear36while differential motion is allowed.

The operation state of the actuator6is detected by the position sensor9. The position sensor9outputs an electric signal to the controller101via the wire103in accordance with the axial position of the armature63. The signal state of the position sensor9is switched on and off in accordance with the distance between the detection surface91aof the position sensor9and the end surface632eof the side plate portion632of the armature63.

In adjusting the position of the position sensor9in the axial direction, as in the first embodiment, a coupled state in which the meshing teeth510aof the engagement/disengagement member50and the meshing teeth353of the first side gear35are meshed with each other in the circumferential direction may be established first by supplying the electromagnet61with an excitation current, and thereafter the position sensor9may be gradually moved away from the armature63, while the insertion portion91of the position sensor9is turned, from a position at which the position sensor9is closest to the armature63. The position sensor9then is fixed to the sensor attachment member8at the position of the position sensor9at the time when the signal state of the position sensor9is switched. Consequently, position adjustment and fixing work for the position sensor9are completed.

According to the present embodiment described above, the same functions and effects as those according to the first embodiment can be obtained.