Abstract:
[Problem] The present invention relates to a seat lifter capable of changing the height or inclination of an inner side lower arm and outer side lower arm of a seat cushion and addresses the problem of providing a seat lifter wherein the welding position of a rod to a link remains fixed. [Solution] Links (link members) ( 19, 191, 61, 161 ) are provided with shaft sections ( 31   a,    119   b,    61   a,    161   b ) having through holes and are rotatably held on the outer peripheral surfaces of the shaft sections ( 31   a,    119   b,    61   a,    161   b ). Rods ( 53, 69 ) are inserted through the through holes of the links ( 19, 191, 61, 161 ) and welded.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a seat lifter changing height or inclination of a seat cushion using links. 
       BACKGROUND ART 
       [0002]    In a seat lifter changing height or inclination of a seat cushion using links, there is a seat lifter that the movement of a link provided at one side (for example, outer-side) of a width direction of a seat is transmitted, via a rod, to a link provided at the other side (for example, inner side) thereof. 
         [0003]    As a connection structure of the rod and the link, there is a structure, in which an end surface of the rod contacts the link and the abutment portion therebetween is fixed by welding (for example, see Patent Document 1). 
         [0004]    In this structure, the dimension in a width direction of the seat becomes uneven due to variations in dimensional accuracy and assembly accuracy of mechanical parts of the seat, and therefore the end surface of the rod may not be welded to the link. 
         [0005]    Consequently, one structure has been proposed, in which a pin that is rotatably supporting a link is fixed to the link and fitted to an inner peripheral portion of the rod, and then the pin and the rod are fixed by welding (for example, see Patent Document 2). 
         [0006]    According to this structure, the variations in dimensional accuracy and assembly accuracy of mechanical parts of the seat can be absorbed by a length of the pin, and therefore it is possible to weld the rod and the link. 
       CITATION LIST 
     Patent Literature 
       [0007]    Patent Document 1: JP-A-2002-283900 ( FIG. 2 ) 
         [0008]    Patent Document 2: JP-A-2010-274691 ( FIG. 2 ) 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0009]    However, in the invention disclosed in Patent Document 2, the welded position of the rod and the pin is not fixed due to the variations in dimensional accuracy and assembly accuracy of mechanical parts of the seat. Accordingly, there is a problem that it is difficult to perform welding using a jig. 
         [0010]    The present invention has been made to solve the above-described problems, and an object thereof is to provide a seat lifter in which a welded position of a rod is fixed. 
       SOLUTION TO PROBLEM 
       [0011]    In order to solve at least one of the above-described problems, a seat lifter according to one aspect of the present invention is a seat lifter that is capable of changing height or inclination of an inner-side lower arm and an outer-side lower arm of a seat cushion. The seat lifter includes a first link member provided at one side of a width direction of a seat, a second link member provided at the other side of the width direction of the seat and a rod having one end attached to the first link member and the other end attached to the second link member. At least one of the link members includes a shaft portion with a hole and is rotatably held on an outer peripheral surface of the shaft portion. The rod is welded in a state of being inserted into the hole of the link member. 
         [0012]    Other features of the present invention will be more apparent from modes for carrying out the present invention and the accompanying drawings, as described below. 
         [0013]    Furthermore, “the link member” as used herein is not limited to an elongated rod-like member itself that is generally referred to as a link, but includes a component shape in which other components are fixed to an elongated rod-like member. 
       EFFECTS OF INVENTION 
       [0014]    According to the present invention, since at least one of the link members includes the shaft portion with the hole and is rotatably held on the outer peripheral surface of the shaft portion and the rod is welded in a state of being inserted into the hole of the link member, the welded position of the rod is fixed. Further, since the rod is inserted into a rod hole, it is possible to absorb the variation in an axial dimension of the rod. 
         [0015]    Other effects of the present invention will be more apparent from modes for carrying out the present invention and the accompanying drawings, as described below. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0016]      FIG. 1  is a perspective view illustrating a main portion of a seat lifter according to an illustrative embodiment. 
           [0017]      FIG. 2  is a view as seen from a direction of an arrow II in  FIG. 1 . 
           [0018]      FIG. 3  is a sectional view taken along a cutting line in  FIG. 2 . 
           [0019]      FIG. 4  is a sectional view taken along a cutting line IV-IV in  FIG. 2 . 
           [0020]      FIG. 5  is a view explaining the inventive portion of a second embodiment, corresponding to  FIG. 3  of the first embodiment. 
           [0021]      FIG. 6  is a view explaining the inventive portion of the second embodiment, corresponding to  FIG. 4  of the first embodiment. 
           [0022]      FIG. 7  is a view explaining a bush of a third embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment  
       [0023]    Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings.  FIG. 1  is a perspective view illustrating a main portion of a seat lifter according to the first embodiment,  FIG. 2  is a view as seen from a direction (outer-side) of an arrow II in  FIG. 1 ,  FIG. 3  is a sectional view taken along a cutting line in  FIG. 2 , and  FIG. 4  is a sectional view taken along a cutting line IV-IV in  FIG. 2 . 
         [0024]    First, an overall configuration of a seat including a seat lifter according to an illustrative embodiment is described with reference to  FIG. 2 . As shown in  FIG. 2 , an outer-side seat track  1  includes a lower rail  7  provided to a floor viabrackets  3 ,  5  and an upper rail  9  that is engaged with the lower rail  7  to be movable relative to the lower rail  7 . 
         [0025]    A pair of (outer-side and inner-side) seat tracks  1  is provided to the floor. The seat track shown in  FIG. 2  is an outer-side seat track. As shown in  FIG. 3  and  FIG. 4 , an inner-side seat track  101  includes a lower rail  107  and an upper rail  109  that is engaged with the lower rail  107  to be movable relative to the lower rail  107 . 
         [0026]    (Seat Lifter Changing Height of Seat Cushion) 
         [0027]    Returning to  FIG. 2 , a front bracket  10  is provided at a front-side upper portion of the upper rail  9 , and a rear bracket  11  is provided at a rear-side upper portion thereof. One end side of a front link  15  is rotatably attached to the front bracket  10  by using a pin  13 . One end side of a rear link  19  is rotatably attached to the rear bracket  11  by using a pin  17 . The other end side of the front link  15  is rotatably attached to a front portion of an outer-side lower arm  23  of the seat cushion by using a pin  21 . The other end side of the rear link  19  is rotatably attached to a rear portion of the lower arm  23  of the seat cushion by a mounting structure as described below. Accordingly, a four-bar linkage rotation mechanism is configured by the upper rail  9 , the front link  15 , the lower arm  23  and the rear link  19 . 
         [0028]    Similarly, an inner-side lower arm  123  (see  FIG. 1 ) of the seat cushion is also provided to the inner-side seat track  101  via a front link (see  FIG. 4 ) and a rear link  119  (see  FIG. 1 ), and a four-bar linkage rotation mechanism is configured by the inner-side upper rail  109 , the front link, the lower arm  123  and the rear link  119 . 
         [0029]    The outer-side rear link  19  is formed with a sector gear  19   a  centered about a rotation center of a side of the lower arm  23 . The lower arm  23  is provided with a pinion  27  that is screwed to the sector gear  19   a.  The pinion  27  is rotationally driven by a motor (not shown) provided in the lower arm  23 . 
         [0030]    Now, a mounting structure of the rear link  19  and the rear link  119  is described with reference to  FIG. 1  and  FIG. 3 . The rear link  19  is formed with a through-hole  19   b  centered about a rotation center thereof. Additionally, the lower arm  23  is formed with a hole  23   a  that has a diameter slightly greater than that of the through-hole  19   b  of the rear link  19 . 
         [0031]    A bush  31  is attached to the through-hole  19   b  of the rear link  19  and is configured by a cylindrical portion (shaft portion)  31   a  and a collar portion  31   b.  The cylindrical portion  31   a  is inserted into the through-hole  19   b  and both ends thereof are formed as an open face. The collar portion  31   b  is formed at an outer peripheral surface of the cylindrical portion  31   a  and welded to an edge of the through-hole  19   b  of the rear link  19 . In the cylindrical portion  31   a  of the bush  31 , an outer peripheral surface of the protruding part protruded from the through-hole  19   b  of the rear link  19  is fitted to the hole  23   a  of the lower arm  23 , and therefore the rear link  19  is rotatably held. One end side of a rod  53  is inserted into a through-hole of the bush  31  and an outer peripheral surface of the rod  53  and the collar portion  31   b  (link member) of the bush  31  are welded to each other. In the cylindrical portion  31   a  of the bush  31 , an outer peripheral surface of the protruding part protruded from the hole  23   a  of the lower arm  23  is mounted with a push nut  55  that can contact an outer surface of the lower arm  23 . Additionally, in the present embodiment, a bush  57  made of a low-friction material is disposed between an inner peripheral surface of the hole  23   a  of the lower arm  23  and an outer peripheral surface of the bush  31 . 
         [0032]    The rear link  119  is formed integrally with a cylindrical portion (shaft portion)  119   b  by a burring operation. 
         [0033]    Meanwhile, the lower arm  123  is formed with a hole  123   a  that has a diameter slightly greater than that of the cylindrical portion  119   b  of the rear link  119 . 
         [0034]    Then, the cylindrical portion  119   b  of the rear link  119  is inserted into the hole  123   a  of the lower arm  123 , and therefore the rear link  119  is rotatably held. The other end side of the rod  53  is inserted into a through-hole of the cylindrical portion  119   b  of the rear link  119 , and an outer peripheral surface of the rod  53  and the rear link  119  are welded to each other. In the cylindrical portion  119   b  of the rear link  119 , an outer peripheral surface of the protruding part protruded from the hole  123   a  of the lower arm  123  is mounted with a push nut  155  that can contact an outer surface of the lower arm  123 . Additionally, in the present embodiment, a bush  157  made of a low-friction material is disposed between an inner peripheral surface of the hole  123   a  of the lower arm  123  and an outer peripheral surface of the cylindrical portion  119   b  of the rear link  119 . 
         [0035]    Accordingly, the rotation of the rear link  19  is transmitted to the rear link  119  via the rod  53 . Consequently, as the pinion  27  is rotated and the rear link  19  is rotated, the rear link  119  is also rotated via the rod  53 . Therefore, the lower arms  23 ,  123  are raised or lowered relative to the seat track  1 . 
         [0036]    (Seat Lifter Changing Inclination of Seat Cushion) 
         [0037]    Returning to  FIG. 2 , a tilt pan  51  is disposed at the front-side upper portions of the lower arm  23  and the lower arm  123  such that the tilt pan  51  bridges the lower arm  23  and the lower arm  123 . A base portion of the tilt pan  51  is rotatably attached to the lower arm  23  by using a pin  52  and rotatably attached to the lower arm  123  by using a pin (not shown). 
         [0038]    Further, arm portions  51   a,    51   b  (see  FIG. 4 ) are provided at an intermediate portion of the tilt pan  51  with extending toward the seat tracks  1 ,  101 . 
         [0039]    A tilt link  61  is rotatably attached to a front portion of the lower arm  23 . One rotation end side of the tilt link  61  is formed with a sector gear  61   a  centered about a rotation center thereof. The lower arm  23  is provided with a pinion  63  that is screwed to the sector gear  61   a.  The pinion  63  is rotationally driven by a motor (not shown) provided in the lower arm  23 . A pin  65 , which is fitted to the arm portion  51   a  of the tilt pan  51 , is provided in the other rotation end side of the tilt link  61 . 
         [0040]    As shown in  FIG. 1 , a tilt link  161  is rotatably attached to a front portion of the lower arm  123 . A pin (not shown), which is fitted to the arm portion  51   b  of the tilt pan  51 , is provided in the other rotation end side of the tilt link  161 . 
         [0041]    Further, a mechanism for absorbing the difference between the rotation trajectory of the tilt links and the rotation trajectory of the tilt pan is provided to the tilt pan  51 , the tilt link  61  and the tilt link  161 . 
         [0042]    Now, a mounting structure of the tilt link  61  and the tilt link  161  is described with reference to  FIG. 1  and  FIG. 4 . The tilt link  61  is formed with a through-hole  61   b  centered about a rotation center thereof. Further, the lower arm  23  is formed with a hole  23   c  that has a diameter slightly greater than that of the through-hole  61   b  of the tilt link  61 . 
         [0043]    A bush  67  is attached to the through-hole  61   b  of the tilt link  61  and is configured by a cylindrical portion (shaft portion)  67   a  and a collar portion  67   b.  The cylindrical portion  67   a  is inserted into the through-hole  61   b  and both ends thereof are formed as an open face. The collar portion  67   b  is formed at an outer peripheral surface of the cylindrical portion  67   a  and welded to an edge of the through-hole  61   b  of the tilt link  61 . In the cylindrical portion  67   a  of the bush  67 , an outer peripheral surface of the protruding part protruded from the through-hole  61   b  of the tilt link  61  is fitted to the hole  23   c  of the lower arm  23  and therefore the tilt link  61  is rotatably held. One end side of a rod  69  is inserted into a through-hole of the bush  67  and an outer peripheral surface of the rod  69 , and the collar portion  67   b  (link member) of the bush  67  are welded to each other. In the cylindrical portion  67   a  of the bush  67 , an outer peripheral surface of the protruding part protruded from the hole  23   c  of the lower arm  23  is mounted with a push nut  68  that can contact an outer surface of the lower arm  23 . Additionally, in the present embodiment, a bush  71  made of a low-friction material is disposed between an inner peripheral surface of the hole  23   c  of the lower arm  23  and an outer peripheral surface of the bush  67 . 
         [0044]    The tilt link  161  is formed integrally with a cylindrical portion  161   b  by a burring operation. 
         [0045]    Meanwhile, the lower arm  123  is formed with a hole  123   c  that has a diameter slightly greater than that of the cylindrical portion  161   b  of the tilt link  161 . 
         [0046]    Then, the cylindrical portion  161   b  of the tilt link  161  is inserted into the hole  123   c  of the lower arm  123 , and therefore the tilt link  161  is rotatably held. The other end side of the rod  69  is inserted into a through-hole of the cylindrical portion  161   b  of the tilt link  161 , and an outer peripheral surface of the rod  69  and the tilt link  161  are welded to each other. In the cylindrical portion  161   b  of the tilt link  161 , an outer peripheral surface of the protruding part protruded from the hole  123   c  of the lower arm  123  is mounted with a push nut  168  that can contact an outer surface of the lower arm  123 . Additionally, in the present embodiment, a bush  171  made of a low-friction material is disposed between an inner peripheral surface of the hole  123   c  of the lower arm  123  and an outer peripheral surface of the cylindrical portion  161   b  of the tilt link  161 . 
         [0047]    Accordingly, the rotation of the tilt link  61  is transmitted to the tilt link  161  via the rod  69 . Consequently, as the pinion  63  is rotated and the tilt link  61  is rotated, the tilt link  161  is also rotated via the rod  69 . Therefore, a rotation end side of the tilt pan  51  is raised and lowered about the pin  52  of the lower arm  23  side, and a pin (not shown) of the lower arm  123  side, so that a front portion of the seat cushion is inclined. 
         [0048]    According to the above configurations, the following effects will be obtained. 
         [0049]    (1) In both the seat lifter changing the height of the seat cushion and the seat lifter changing the inclination of the seat cushion, the rod  53  and the rod  69  are inserted into the through-holes of the cylindrical portions (shaft portions) of the link member. Since the outer peripheral surfaces of the rod  53  and the rod  69  and the link member are welded to each other, so that the welded positions of the rod  53  and the rod  69  are fixed. 
         [0050]    Further, since the rod  53  and the rod  69  are inserted into the through-holes of the cylindrical portions of the link member, it is possible to absorb the variation in an axial dimension of the rod  53  and the rod  69 . 
         [0051]    (2) Since the rear link  119  is formed integrally with the cylindrical portion  119   b,  it is possible to reduce the number of parts and it is possible to stably hold the rear link  119  and the rod  53 . 
         [0052]    Since the tilt link  161  is formed integrally with the cylindrical portion  161   b,  it is possible to reduce the number of parts and it is possible to stably hold the tilt link  161  and the rod  69 . 
         [0053]    (3) Since the cylindrical portion  119   b  of the rear link  119  is formed by a burring operation, manufacturing is simple. Similarly, since the cylindrical portion  161   b  of the tilt link  161  is also formed by a burring operation, manufacturing is simple. 
         [0054]    (4) The rear link  19  having the sector gear  19   a  formed thereon and the tilt link  61  having the sector gear  61   a  formed thereon are subjected to a process of increasing the hardness by quenching. As the quenching is performed, a peripheral surface of the shaft portion is hardened, and therefore an inner peripheral side of the push nut does not bite into the shaft portion. Consequently, the push nut does not perform a push nut function. However, in the present embodiment, since the bush  31  and the bush  67  are interposed, the cylindrical portion  31   a  and the cylindrical portion  67   a  that are not hardened can be formed in the rear link  19  and the tilt link  161 . In addition, it is possible to cause the welded positions of the rod  53  and the rod  69  to be fixed and it is also possible to absorb the variation in an axial dimension of the rod  53  and the rod  69 . 
         [0055]    The present invention is not limited to the above-described embodiments. Although the bush  31  and the bush  67  respectively include the collar portion  31   b  and the collar portion  67   b  in the above-described embodiment, the collar portion  31   b  and the collar portion  67   b  may be omitted. 
         [0056]    Further, although a cylindrical portion is formed integrally in one side of the links and a cylindrical portion is formed in the bush that is fixed to the other side of the links in the present embodiment, the cylindrical portions may be formed integrally in both links without using the bush. In addition, both of the links may be a link that includes a bush having a cylindrical portion formed therein without forming the cylindrical portions integrally in the links. 
         [0057]    Further, in the seat lifter of the above-described embodiment, the link is rotationally driven by rotationally driving a pinion that is meshed with the sector gear formed on the link. However, in addition to this configuration, the seat lifter may include a fixing nut member, which is only allowed to rotate and a threaded bar, which is screwed to the fixing nut member and has an end portion rotatably attached to the link. Therefore, the link may be rotated by rotating the fixing nut member to advance and retreat the threaded bar. 
         [0058]    Further, although the rear link  19  is rotated in the mechanism changing the height of the seat cushion in the above-described embodiment, either one of the front link and the rear link to configure the four-bar linkage rotation mechanism may be rotated. 
         [0059]    Furthermore, although the holes into which the rod  53  and the rod  69  are inserted are through-holes in the above-described embodiment, the holes may be blind holes having a sufficient depth. 
       Second Embodiment 
       [0060]    A second embodiment is described with reference to  FIG. 5  and  FIG. 6 .  FIG. 5  is a view explaining the inventive portion of the second embodiment, and it is corresponding to  FIG. 3  of the first embodiment.  FIG. 6  is a view explaining the inventive portion of the second embodiment, and it is corresponding to  FIG. 4  of the first embodiment. 
         [0061]    The present embodiment is the same as the first embodiment except for the shape of the bush. Accordingly, the same or similar element will be denoted by the same reference numeral as that of the first embodiment and a duplicated description thereof will be omitted. 
         [0062]    First, as shown in  FIG. 5 , a bush  231  is attached to the through-hole  19   b  of the rear link  19  and is configured by a cylindrical portion (shaft portion)  231   a  and a collar portion  231   b.  The cylindrical portion  231   a  is inserted into the through-hole  19   b  and both ends thereof are formed as an open face. The collar portion  231   b  is formed at an outer peripheral surface of the cylindrical portion  231   a.    
         [0063]    The cylindrical portion  231   a  at one side portion of the collar portion  231   b  is inserted into the hole  19   b  of the rear link  19  and the one side portion of the collar portion  231   b  is welded to an edge of the through-hole  19   b  of the rear link  19 . 
         [0064]    Further, the cylindrical portion  231   a  at the other side portion of the collar portion  231   b  is inserted through the hole  23   a  of the lower arm  23 . An outer peripheral surface of the part of the cylindrical portion  231   a  protruded from the hole  23   a  of the lower arm  23  is mounted with the push nut  55  that can contact an outer surface of the lower arm  23 . Accordingly, since the lower arm  23  is sandwiched between the push nut  55  and the collar portion  231   b  of the bush  231 , an axial movement of the bush  231  is restricted and the other side portion of the collar portion  231   b  and a peripheral part of the hole  23   a  of the lower arm  23  are in sliding contact with each other. Additionally, in the present embodiment, the bush  57  made of a low-friction material is disposed between an inner peripheral surface of the hole  23   a  of the lower arm  23  and an outer peripheral surface of the bush  31 . 
         [0065]    Next, as shown in  FIG. 6 , a bush  267  is attached to the through-hole  61   b  of the tilt link  61  and is configured by a cylindrical portion (shaft portion)  267   a  and a collar portion  267   b.  The cylindrical portion  267   a  is inserted into the through-hole  61   b  and both ends thereof are formed as an open face. The collar portion  267   b  is formed at an outer peripheral surface of the cylindrical portion  267   a.    
         [0066]    The cylindrical portion  267   a  at one side portion of the collar portion  267   b  is inserted into the hole  61   b  of the tilt link  61 , and the one side portion of the collar portion  267   b  is welded to an edge of the through-hole  61   b  of the tilt link  61 . 
         [0067]    Further, the cylindrical portion  267   a  at the other side portion of the collar portion  267   b  is inserted through the hole  23   c  of the lower arm  23 . An outer peripheral surface of the part of the cylindrical portion  267   a  protruded from the hole  23   c  of the lower arm  23  is mounted with the push nut  68  that can contact an outer surface of the lower arm  23 . Accordingly, since the lower arm  23  is sandwiched between the push nut  68  and the collar portion  267   b  of the bush  267 , an axial movement of the bush  267  is restricted and the other side portion of the collar portion  267   b  and a peripheral part of the hole  23   c  of the lower arm  23  are in sliding contact with each other. Additionally, in the present embodiment, the bush  71  made of a low-friction material is disposed between an inner peripheral surface of the hole  23   c  of the lower arm  23  and an outer peripheral surface of the bush  31 . 
         [0068]    According to the above configurations, in addition to the effects of the first embodiment, the following effects can be obtained. 
         [0069]    (1) When a seat is raised and lowered, the collar portion  231   b  of the bush  231  and the collar portion  267   b  of the bush  267  are brought into sliding contact with the lower arm  23 . Since the collar portion  231   b  of the bush  231  and the collar portion  267   b  of the bush  267  are formed by machining or the like (for example, cold forging), perpendicularity for the cylindrical portion  231   a  and the cylindrical portion  267   a  becomes good. Accordingly, when the seat is raised and lowered, the seat can be smoothly raised and lowered, generation of noise is suppressed and a lifting driving force is also reduced. 
         [0070]    (2) Since the thickness of the collar portion  231   b  of the bush and the collar portion  267   b  of the bush  267  is changed, the amount of offset between the lower arm  23  and the rear link  19  and tilt link  61  can be easily changed. 
         [0071]    In addition, although the holes into which the rod  53  and the rod  69  are inserted are through holes in the above-described embodiment, the holes may be blind holes having a sufficient depth. 
       Third Embodiment  
       [0072]    A third embodiment is described with reference to  FIG. 7 .  FIG. 7  is a view explaining a bush of the third embodiment. The present embodiment is the same as the first and second embodiments except for the shape of the bush. Accordingly, the same or similar element will be denoted by the same reference numeral as that of the first and second embodiments and a duplicated description thereof will be omitted. 
         [0073]    In  FIG. 7 , a bush  331  includes a cylindrical portion (shaft portion)  331   a  whose both ends are formed as an open face, and a collar portion  331   b  formed at an outer peripheral surface of the cylindrical portion  331   a.  Furthermore, the cylindrical portion  331   a  includes a large-diameter section  331   c  formed at one side with respect to the collar portion  331   b  and a small-diameter section  331   d  formed at the other side, which has a diameter smaller than the large-diameter section  331   c.    
         [0074]    The large-diameter section  331   c  of the cylindrical portion  331   a  of the bush  331  is inserted into the through-hole  19   b  of the rear link  19 . Then, one side portion (side portion on the large-diameter section  331   c  side) of the collar portion  331   b  is welded to an edge of the through-hole  19   b  of the rear link  19 . 
         [0075]    Further, the small-diameter section  331   d  of the cylindrical portion  331   a  of the bush  331  is inserted through the hole  23   a  of the lower arm  23 . An outer peripheral surface of the part of the small-diameter portion  31   d  protruded from the hole  23   a  of the lower arm  23  is mounted with the push nut  55  that can contact an outer surface of the lower arm  23 . Accordingly, since the lower arm  23  is sandwiched between the push nut  55  and the collar portion  331   b  of the bush  331 , an axial movement of the bush  231  is restricted, and the other side portion of the collar portion  231   b  and a peripheral part of the hole  23   c  of the lower arm  23  are in sliding contact with each other. 
         [0076]    Meanwhile, although  FIG. 7  is described with reference to the rear link  19 , the same configurations may be applied to the tilt link  61 . 
         [0077]    According to the above configurations, since the part of the cylindrical portion  331   a  of the bush  331  that is rotatably held in the lower arm  23  is formed as the small-diameter section  331   d,  it is possible to reduce the hole  23   a  of the lower arm  23 . Therefore, it is possible to achieve the miniaturization and strength-up of the lower arm  23 . 
         [0078]    In addition, although the holes into which the rod  53  and the rod  69  are inserted are through-holes in the above-described embodiment, the holes may be blind holes having a sufficient depth. 
         [0079]    The present invention is not limited to the first to third embodiments and but can be practiced with various modifications within the spirit of the present invention and the scope described in the claims. 
         [0080]    Reference Numerals List
     19  Rear Link     31 ,  67  Bush     31   a,    67   a,    119   b,    161   b  Shaft Portion   Tilt Link     119  Rear Link   Tilt Link     53 ,  69  Rod