Coupling structure between seatback and armrest for vehicle

A structure where an armrest is detachably coupled to a seatback includes an axial pin, a moving pin, a supporting bracket, and a slope. The axial pin and the moving pin projects from a side face of one end of the armrest. The moving pin has a head at its distal end. The supporting bracket is fixed on a side portion of the seatback, and it has an axial hole for receiving the axial pin and a guide groove for receiving the moving pin. The axial pin is inserted into the axial hole to be rotatably supported by the supporting bracket. The moving pin is inserted into the guide groove to be moved within the guide groove according to rotation of the axial pin. The slop is disposed on an edge of the guide groove near the using point. As the armrest reaches the using position, the head rides on the slope according to movement of the moving pin, so that the moving pin approaches to the seatback. Thereby, the slope causes the armrest at the using position and the side portion of the seatback to contact with each other and the armrest is supported on the side portion of the seatback.

BACKGROUND OF THE INVENTION
 The present invention relates to a coupling structure between a seatback
 and an armrest for a vehicle.
 DESCRIPTION OF THE RELATED ART
 In a conventional structure where a seatback and an armrest are detachably
 coupled with each other, the seatback is formed at its one side portion
 with an axial hole and the armrest has an axial pin inserted into the
 axial hole. Inside the axial hole, a locking mechanism releasably engaged
 with the axial pin is provided. The armrest is rotatably supported in the
 axial hole in a state where the axial pin is prevented from coming out of
 the axial hole by the locking mechanism. The armrest is used in a state
 where it is maintained in a using position
 SUMMARY OF THE INVENTION
 In the above conventional structure, however, the armrest maintained at the
 using position tends to generate play.
 Also, in a case that the armrest can not be attached to one side portion of
 the seatback for spatial reasons, a space is required for accommodating
 the armrest which has been detached.
 Therefore, one object of the present invention is to provide a coupling
 structure capable of suppressing play of the armrest maintained at the
 using position. Also, another object of the invention is to provide a
 coupling structure where it is unnecessary to provide a space for
 accommodating the armrest.
 In order to achieve the above objects, a first aspect of the invention
 relates to a coupling structure between a seatback and an armrest for a
 vehicle. The armrest is detachably attached to the seatback. The structure
 comprises an axial pin, a moving pin, a supporting bracket, and a slope.
 The axial pin and the moving pin project from a side face positioned at
 one end of the armrest. The moving pin has a head at its distal end. The
 supporting bracket is fixed on a side portion of the seatback and is
 provided with an axial hole for receiving the axial pin and a guide groove
 for receiving the moving pin. The axial pin is inserted into the axial
 hole to be rotatably supported by the supporting bracket. The moving pin
 is inserted into the guide groove to be moved within the guide groove
 according to rotation of the axial pin. When the armrest is put at the
 using position, the moving pin is maintained at a using point within the
 guide groove. The slope is disposed on an edge of the guide groove in the
 vicinity of the using point. When the armrest reaches the using position,
 the head rides on the slop according to movement of the moving pin, so
 that the moving pin approaches to the seatback. Thereby, the slope brings
 the armrest at the using position and the side portion of the seatback
 into contact with each other.
 According to the above structure, at the using position of the armrest, the
 head of the moving pin rides on the slope, the moving pin approaches to
 the seatback, and the armrest comes into contact with the side portion of
 the seatback. Therefore, the armrest is supported by the side portion of
 the seatback, and the play is prevented from occurring in the armrest at
 the using position.
 The moving pin may be structured with the head and a moving shaft, and the
 guide groove may have a head receiving hole through which the head is
 allowed to pass. The head projects from a distal end of the moving shaft
 in a radial direction thereof. The portion of the guide groove except for
 the head receiving hole allows movement of the moving shaft and prevents
 passing-through of the head. When the axial pin is inserted into the axial
 hole and the head passes through the head receiving hole, the armrest
 reaches a detaching position thereof. The movement of the moving shaft
 from the head receiving hole to the using point causes rotational movement
 of the armrest from the detaching position to the using position around
 the axial hole.
 The guide groove may have an accommodating point between the head receiving
 hole and the using point, and a neck portion adjacent to the receiving
 point between the head receiving hole and the accommodating point. The
 moving shaft may include a base portion and an intermediate portion
 between the head and the base portion. The coupling structure may be
 provided with a biasing member. The intermediate portion has a diameter
 larger than that of the base portion. The portion of the guide groove
 positioned between the using point and the accommodating point allows
 movement of the intermediate portion. The neck portion allows movement of
 the base portion and prevents movement of the intermediate portion. The
 biasing member presses the moving pin positioned at the accommodating
 point in a direction opposed to the seatback.
 According to the above structure, in an ordinary using state, the
 intermediate portion is positioned between the using point and the
 accommodating point, so that the moving pin is allowed to move between
 both the points. Also, in the accommodating point, since the moving pin is
 pressed in a direction opposed to the seatback by the biasing member, the
 intermediate portion is maintained within the guide groove so that the
 base portion is prevented from moving into the guide groove. Therefore,
 the intermediate portion and the neck portion prevent the moving pin from
 moving from the accommodating point to the head receiving hole.
 Accordingly, in the using state, the moving pin is prevented from going
 out of the guide groove, so that the armrest is prevented from coming out
 of the seatback unnecessarily.
 When the armrest is detached from the seatback, the armrest is pushed
 towards the seatback in a state where the moving pin is put in the
 accommodating point. Thereby, the moving pin is moved against the biasing
 force of the biasing member and the base portion reaches the guide groove.
 In such a state, when the moving pin is pushed towards the head receiving
 hole, the base portion passes through the neck portion to arrive at the
 head receiving hole. The armrest is easily detached from the seatback by
 pulling the moving pin out of the head receiving hole.
 When the armrest is put in its accommodating position, the moving pin is
 pressed by the biasing member in the direction opposed to the seatback. In
 such a state, as the head is supported on an edge of the guide groove, the
 play is prevented from occurring in the armrest in the accommodating
 position.
 The other end of the armrest in the using position may be directed to the
 frontal face of the seatback. When the intermediate portion is positioned
 at the accommodating point, the armrest may be positioned in the
 accommodating position with its other end facing upwardly. The armrest
 positioned at the detaching position may be inclined towards the back face
 of the seatback rather than the accommodating position.
 The biasing member may comprise a spring plate disposed between the guide
 groove and the seatback.
 According to the above structure, the biasing member can easily be disposed
 in a small clearance.
 The spring plate may cover the whole area of the guide groove.
 According to the above structure, in the supporting bracket from which the
 armrest is detached, the guide groove is put in a state where it is
 covered with the spring plate, so that the inside of the guide groove is
 not exposed outwardly. Accordingly, the appearance of the seatback is
 improved and dust or the like is hard to accumulate in the guide groove.
 The spring plate may press the head towards the guide groove in contact
 with the head.
 The spring plate may press the moving pin positioned between the
 accommodating point and the using point in the direction opposed to the
 seatback.
 A coupling structure according to a second aspect of the invention
 comprises first and second supporting mechanisms and a coupling mechanism.
 The supporting mechanisms are respectively provided at both side portions
 of a seatback. The coupling mechanism is provided at a side face of one
 end of an armrest. The coupling mechanism is selectively and detachably
 coupled to the supporting mechanisms.
 According to the above structure, as the armrest is selectively attachable
 to both the side portions of the seatback, when the armrest can not be
 attached to one side portion of the seatback for spatial reasons, it may
 be attached to the other side portion. Accordingly, it is unnecessary to
 accommodate the armrest in a passenger compartment or a baggage room of a
 vehicle. Also, generation of uncomfortable noises during running of the
 vehicle or deformation of the armrest is prevented.
 A seat including the seatback can be rotatably supported on a floor of the
 vehicle, and rotational movement of the seat may cause change in a frontal
 direction of the seatback.
 According to the above structure, when the armrest attached to one side
 portion of the seatback interferes with a portion of a vehicle body
 according to rotation of the seat, the armrest may be switched and
 attached to the other side portion of the seatback.
 The coupling mechanism may have the axial pin and the moving pin of the
 first aspect, and each supporting mechanism may have the supporting
 bracket and the slope of the first aspect.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 An embodiment of the present invention will be explained with reference to
 the drawings below.
 In FIG. 1, a right side front seat 1 disposed in a wagon vehicle having a
 right side steering wheel is shown. An armrest 3 is rotatably or pivotably
 attached to a left side portion of a seatback 2. The armrest 3 is
 rotationally movable from a using position 30 to a detaching position 32
 through an accommodating position 31.
 As shown in FIG. 2, the front seat 1 at an ordinary time faces to a frontal
 direction 33 of the vehicle, and a front direction 35 of the seatback 2
 corresponds to the frontal direction 33. As shown in FIG. 3, the front
 seat 1 during a stop state of the vehicle is made rotatable around a
 fulcrum 50 so as face in a rear direction 34 of the vehicle (the front
 direction of the seatback 2 corresponding to the front direction 35). When
 the front seat 1 is directed in the rear direction 34, the armrest 3 is
 detached from the left side portion and it is attached to a right side
 portion of the seatback 2. The detachment is effected because the armrest
 3 which has been attached to the left side portion interferes with a door
 4 of the vehicle during rotation of the seat 1.
 As shown in FIG. 4, such a structure that the armrest 3 is selectively
 attachable to the left and right side portions of the seatback 2 is
 established by a coupling mechanism 51 provided in the armrest 3, and
 first and second supporting mechanisms 52, 53 provided respectively on the
 left and right side portions of the seatback 2.
 First, the coupling mechanism 51 on the armrest 3 will be explained with
 reference to FIGS. 4 to 8.
 A base 5 is fixed on a side face 3a of a base end of the armrest 3. An
 axial pin 6 and a moving pin 7 project from the base 5. The axial pin 6
 has a simple cylindrical shaft configuration, and the moving pin 7 has a
 generally mushroom configuration. The respective proximal ends of the pins
 6, 7 are supported by a bracket 8, and respective intermediate portions
 thereof are supported by a reinforce 9. The bracket 8 and the reinforce 9
 are fixed to the base 5.
 The armrest 3 has a symmetrical shape with respect to a straight line 54
 (shown in FIG. 4) connecting the axial pin 6 and the moving pin 7. Faces
 3b, 3b on which an arm of a passenger rests are formed on both sides of
 the armrest 3. When the armrest 3 is attached to the seatback 2, it is
 combined with a cover 10 (shown in FIG. 13).
 As shown in FIGS. 7A and 7B, the moving pin 7 comprises a moving shaft 40
 extending from the base 5 and a head 11 provided at a distal end of the
 moving shaft 40. The moving shaft 40 comprises a base portion 13 and an
 intermediate portion 12 connecting the base portion 13 and the head 11.
 The diameter 41 of the head 11 is larger than the diameter 42 of the
 intermediate portion 12, and the diameter 42 of the intermediate portion
 12 is larger than the diameter 43 of the base portion 13 (the
 diameter41&gt;the diameter42&gt;the diameter 43). The diameter 41 of the
 head 11 is larger than the width of a guide groove 56 (shown in FIG. 7B)
 described later, and the diameter 42 of the intermediate portion 12 is
 smaller than the width of the guide groove 56. A pair of projections 14
 towards the guide groove 56 are formed on the back face of the head 11. A
 distal end of each projection 14 contacts with an edge of the guide groove
 56. A clearance 29 corresponding to the height of the projection 14 is
 secured between the edge of the guide groove 56 and an outer edge 11a of
 the head 11.
 Next, the first and second supporting mechanisms 52 and 53 on the left and
 right side portions of the seatback 2 will be explained with reference to
 FIG. 4.
 As shown in FIG. 4, the first and second supporting mechanisms 52, 53
 respectively comprise metallic spring plates 15a, 15b serving as biasing
 members, metallic armrest brackets 16a, 16b, and resin-made armrest
 finishers 17a, 17b. The armrest brackets 16a, 16b and the armrest
 finishers 17a, 17b respectively constitute left and right supporting
 brackets 60a, 60b. The left and right corresponding parts have left and
 right symmetrical configurations.
 These elements are arranged on the side portions of the seatback 2 in the
 order of the spring plates 15a, 15b, the armrest brackets 16a, 16b and the
 armrest finishers 17a, 17b. The spring plates 15a, 15b and the armrest
 finishers 17a, 17b are respectively attached to the armrest brackets 16a,
 16b . The lower portions of the armrest brackets 16a, 16b are respectively
 fixed to the side portions of the seatback 2 by bolts (not shown). Upper
 portions of the armrest brackets 16a, 16b are respectively engaged with
 resin brackets 23a, 23b fixed to the side portions of the seatback 2.
 Each of the biasing members configured by the spring plates 15a, 15b is
 suitable for placement in a narrow space. When the armrest 2 is positioned
 between the using position 30 and the accommodating position 31 (shown in
 FIGS. 1 and 9), each of the spring plates 15a, 15b imparts a biasing force
 44 (shown in FIGS. 12 and 14) on the moving pin 7 in a direction opposed
 to the seatback 2. As a conventional locking mechanism engaged with the
 axial pin 10 of the armrest 3 is not required for the seatback 2, the
 seatback 2 has a simple structure.
 Next, the first and second supporting mechanisms 52, 53 will be explained
 in detail. Since the supporting mechanisms 52, 53 have almost the same
 structure, explanation of the second supporting mechanism 53 will be
 omitted and the first supporting mechanism 52 will be explained.
 As shown in FIGS. 9 and 10, a hole 18 and a groove 19 are formed in the
 armrest bracket 16a. The groove 19 extends along a circular arc about the
 hole 18. The groove has a hole portion 47 at its one end and a neck 26
 adjacent thereto. The portion of the groove 19 positioned between the
 other end of the groove 19 and the neck 26 has almost the same width, the
 width of the neck 26 is smaller than that of the other end, and the
 diameter of the hole portion 47 is larger than the width of the other end.
 As shown in FIG. 11, a hole 20 corresponding to the hole 18 and a cutout 21
 corresponding to the groove 19 are formed in the armrest finisher 17a. As
 shown in FIGS. 13, 14, the armrest finisher 17a has a wall 55 bent from a
 peripheral portion of the cutout 21 towards the armrest bracket 18, and
 the wall 55 contacts with an inner face of the groove 55.
 The inner face of the wall 55 defines the guide groove 56 of the supporting
 bracket 60a. As shown in FIG. 15, an inner face of the wall 55
 corresponding to the neck 26 of the groove 19 defines a neck portion 57 of
 the supporting bracket 60a. As shown in FIG. 16, an inner face of the wall
 55 corresponding to the hole portion 47 of the groove 19 defines a head
 receiving hole 58 of the supporting bracket 60a.
 As shown in FIG. 9, the guide groove 56 has the head receiving hole 58 at
 its one end, the neck portion 57 adjacent thereto, an accommodating point
 39 adjacent to the neck portion 57, and a using point 46 at the other end.
 The diameter of the head receiving hole 58 is larger than the diameter 41
 (shown in FIG. 7A) of the head 11 and, therefore, the head receiving hole
 58 allows passing-through of the head 11. The width of the portion of the
 guide groove 56 positioned between the using point 46 and the
 accommodating point 39 is smaller than the diameter 41 (shown in FIG. 7A)
 of the head 11 and is larger than the diameter 42 (shown in FIG. 7A) of
 the intermediate portion 12. Therefore, the portion of the guide groove 56
 between the using point 46 and the accommodating point 39 prevents
 passing-through of the head 11 and allows movement of the intermediate
 portion 12. The minimum width of the neck portion 57 is smaller than the
 diameter 42 of the intermediate portion 12 (shown in FIG. 7A) and larger
 than the diameter 43 of the base portion 13. Therefore, the neck portion
 57 allows movement of the base portion 13 and prevents movement of the
 intermediate portion 12.
 As shown in FIG. 11, the spring plate 15a has a hole 25 corresponding to
 the holes 18, 20 and it covers the guide groove 56 (the groove 19 and the
 cutout 21).
 As shown in FIGS. 11 and 13, a cylindrical portion 22 projects from a
 peripheral portion of the hole 20 towards the seatback 2 to be inserted
 into the holes 18, 25. An inner peripheral face of the cylindrical portion
 22 defines an axial hole 59 for rotatably supporting the axial pin 6.
 As shown in FIGS. 4 and 9, a recessed portion 24 engaged with a resin
 bracket 23a is formed at an upper portion of the armrest bracket 16a. As
 the upper portion of the armrest bracket 16a is supported by the resin
 bracket 23a having a low strength, the rigidity of the side portion of the
 seatback 2 is not increased excessively. Accordingly, when a load is
 imparted on the seatback 2 (shown in FIG. 2) in the rear direction 34,
 deformation of the resin bracket 23a allows rearward deformation of the
 seatback 2, so that the load acting in the rear direction 34 can securely
 be absorbed.
 Also, since the upper portion of the armrest bracket 16a is fixed to the
 seatback 2 within a range of the strength of the resin bracket 23a, the
 rigidity of the armrest bracket 16a required for use is secured
 sufficiently.
 As shown in FIG. 9, the intermediate portion 12 of the guide groove 56 may
 move within an ordinary range defined between the accommodating point 39
 and the using point 46. When the intermediate portion 12 is positioned at
 the using point 46, the armrest 13 is positioned at the using position 30
 where the other end thereof faces in the frontal direction 35. When the
 intermediate portion 12 is positioned at the accommodating point 39, the
 armrest 3 is positioned at the accommodating position 31 where the other
 end faces upwardly along the seatback 2. The neck portion 57 prevents the
 intermediate portion 12 positioned within the ordinary range 36 from
 moving to a detaching range 37 between the accommodating point 12 and the
 head receiving hole 47.
 The spring plate 15a applies biasing force 44 (shown in FIG. 12) on the
 moving pin 7 in the direction opposed to the seatback 2 only within the
 ordinary range 36 while it is put in contact with the head 11. In the
 state where the head 11 is applied with the biasing force 44 from the
 spring plate 15a, the projections 14 are brought into close contact with
 the edges of the guide groove 56 (the edges of the groove 19 of the
 armrest bracket 16a).
 A slope 28 rising towards the seatback 2 is formed on an edge of the groove
 19 near the using point 46 . The slope 28 has an inclination portion 27
 gradually approaching to the seatback 2 from the accommodating point 39
 along the direction to the using point 46. The inclination portion 27 and
 the slope 28 are formed at each of both sides of the groove 19.
 Next, operation of this embodiment will be explained mainly with reference
 to FIGS. 13 to 16. In the following description, explanation will be made
 on the armrest 3 disposed at the left side portion of the seatback 2
 directed forward, as show in FIG. 2.
 As shown in FIGS. 13 and 14, when the axial pin 6 is inserted into the
 axial hole 59, and the base portion 13 or the intermediate portion 12 of
 the moving pin 7 is positioned in the guide groove 56, the moving pin 7 is
 movable within the ordinary range 36 between the using point 30 and the
 accommodating point 31, and the armrest 3 is rotationally movable between
 the using position 30 and the accommodating position 31 about the axial
 hole 59. In the ordinary range 36, since the diameter of the head 11 of
 the moving pin 7 is larger than the width of the guide groove 56, the
 armrest 3 is prevented from coming off.
 Furthermore, as shown in FIG. 13, when the moving pin 7 moves to the using
 point 46 (the armrest 3 is moved to the using position 30), the head 11
 (the projections 14) rides on the slope 28 along the inclination portion
 27 and the moving pin 7 moves towards the seatback 2. Therefore, the
 armrest 3 contacts with the side portion (the armrest finisher 17a) of the
 seatback 2. Accordingly, in the using position 30, the armrest 3 is
 supported by the side portion of the seatback 2, so that play of the
 armrest 3 is prevented from occurring along the transverse direction of
 the vehicle (the width direction of the seatback 2).
 When the armrest 3 is not used, the armrest 3 is first rotated upward to be
 moved up the accommodating position 31. When the armrest 3 is moved to the
 accommodating position 31, the moving pin 7 slides down on the slope 28
 along the inclination portion 27.
 As shown in FIG. 12, the clearance 29 corresponding to the height of the
 projection 14 suppresses generation of a strong interference between the
 edges of the slope 28 including the inclination portion 27 and of the
 guide groove 56 and an outer edge 11a of the head 11 while the moving pin
 7 is moving along the inclination portion 27. Therefore, the moving pin 7
 moves smoothly. As the clearance 29 is formed so as to correspond to the
 outer edge 11a of each side of the head 11, the strong interference
 between the outer edge 11a, and the inclination portion 27 and the like is
 suppressed both in a case where the head slides up along the inclination
 portion 27 and in a case where it slides down there along. Accordingly,
 the armrest 3 is rotationally operated smoothly.
 As shown in FIG. 14, the moving pin 7 which has reached the accommodating
 point 39 (shown in FIG. 9) is subjected to the biasing force 44 by the
 spring plate 15a. As a result, the play of the armrest 2 positioned at the
 accommodating position 31 is also prevented from occurring in the
 transverse direction of the vehicle. When the moving pin 7 at the
 accommodating point 39 is pressed towards the seatback 2 with a force
 exceeding the biasing force 44 of the spring plate 15a the armrest 3
 approaches to the seatback 2.
 When the armrest 3 is detached from the seatback 2, the armrest 3 at the
 accommodating point 39 which is an entrance of the neck portion 26 is
 pressed towards the seatback 2 with a force exceeding the biasing force 44
 and the base portion 13 is moved into the guide groove 56. In such a
 state, when the moving pin 7 is pressed to the detaching range 37, as
 shown in FIG. 15, since the base portion 13 passes through the neck
 portion 26, the moving pin 7 passes through the neck portion 26 to move
 into the head receiving hole 58 (shown in FIG. 16). Since the head
 receiving hole 58 allows passing-through of the head 11, the moving pin 7
 within the head receiving hole 58 is pulled in a direction apart from the
 seatback 2, so that the moving pin 7 is pulled out of the head receiving
 hole 58. Thus, the armrest 3 is easily detached from the seatback 2.
 After the armrest 3 is detached, the armrest finisher 17a is exposed.
 However, as the spring plate 15a covers the whole of the guide groove 56
 (the groove 19 and the cutout 21), the inside of the guide groove 56 is
 not exposed. Thus, the appearance of the seatback 2 is improved and dust
 or the like is hard to accumulate in the guide groove 56 (the groove 19).
 Since the armrest 3 can selectively be attached to the left and right side
 portions of the seatback 2, it is unnecessary to provide a space for
 accommodating the armrest 3 detached from one of the side portions in the
 passenger compartment of the baggage room of the vehicle. And, since the
 armrest 3 detached is not put in the passenger compartment or the like,
 uncomfortable noises generated by movement of the armrest 3 due to
 vibrations generated during a running situation of the vehicle can be
 suppressed. Furthermore, the axial pin 6 or the moving pin 7 is prevented
 from deforming due to the movement of the armest 3, so that rotational
 operationability of the armrest 3 attached to the seatback 2 does not
 deteriorate.
 In the embodiment, the above explanation has been made on the front seat 1
 which is changeable in its orientation by rotation, but the prevent
 invention is applicable to a seat changeable in its orientation by another
 method except for the rotation. Also, the present invention is not limited
 to the front seat 1, but it is also applicable to a second seat or a third
 seat.