Abstract:
First and second lower support mechanisms ( 27, 28 ): are each provided with a coil spring ( 66, 86 ) that is mated to the outer periphery of an axle part ( 59, 79 ) of a fulcrum bolt ( 53, 73 ); and are configured in such a manner that support brackets ( 51, 71 ) are able to rock with respect to a steering column ( 5 ) by compressing the coil springs ( 66, 86 ). The coil springs ( 66, 86 ) are formed in such a manner that the axle parts ( 59, 79 ) are force fitted in a state prior to column-side fastening parts ( 55, 75 ) being fastened to the steering column ( 5 ).

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a steering device for a vehicle. 
       BACKGROUND ART 
       [0002]    A steering device has been known which has a tilt function of enabling a height position of a steering wheel to be adjusted depending on a physical size of a driver and the like. In the steering device, a steering column that rotatably supports a steering shaft is tiltably supported to a vehicle main body and a tilt angle of the steering column is changed to adjust the height position of the steering wheel. 
         [0003]    A support structure of a fulcrum part of the steering column has been known which is supported to the vehicle main body via a pair of support mechanisms provided at both sides of the vehicle in a left-right direction (for example, refer to Patent Document 1). 
         [0004]    In the steering device of Patent Document 1, as shown in  FIG. 9 , each support mechanism  91  includes a substantially L-shaped support bracket  96  having a column-side fastening part  93  that is tiltably fastened to a steering column  92  and a vehicle body-side fastening part  95  that is fastened to a fixing member  94  fixed to a vehicle main body. Also, the support mechanism  91  includes a fulcrum bolt  98  that is inserted into an axle hole  97  formed in the column-side fastening part  93 , a collar  99  that is fitted to an outer side of the fulcrum bolt  98  and a cylindrical bush  100  that is interposed between the collar  99  and the axle hole  97 . The bush  100  is made of a resin material having an excellent sliding property and is configured so that the collar  99  (fulcrum bolt  98 ) is rotatably inserted therein. In the meantime, the bush  100  has a cylindrical part  101  and flange parts  102  that extends from both axial ends of the cylindrical part in a diametrically outer direction. 
         [0005]    In the support bracket  96 , the column-side fastening part  93  is fastened to the steering column  92  by the fulcrum bolt  98  and the vehicle body-side fastening part  95  is fastened to the fixing member  94  by a fastening bolt  103 . Thereby, the steering column  92  is tiltably supported to the vehicle main body about the fulcrum bolt  98  by the support mechanism  91 . 
       CITATION LIST 
     Patent Documents 
       [0000]    
       
         Patent Document 1: JP-A-2009-113726 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    However, as shown with the dashed-two dotted line in  FIG. 9 , for example, the fixing member  94  is deviated from a normal position (a position in a case where there is no processing error and the like) due to processing precision, mounting precision to the vehicle main body and the like, so that a fastening surface  94   a  of the fixing member  94  before the fastening becomes non-parallel with (is inclined to) a fastening surface  95   a  of the vehicle body-side fastening part  95  arranged at the normal position. When the fastening surface  94   a  and the fastening surface  95   a  are not parallel with each other, the support bracket  96  may be deformed or deform the cylindrical part  101  and flange parts  102  of the bush  100  upon the fastening of the support bracket  96  to the fixing member  94 , so that the support bracket  96  is oscillated. As a result, an axial force of the fastening bolt  103  is counterbalanced by stress, which is accompanied by the deformation of the support bracket  96  or bush  100 , so that the fastening force of the support bracket  96  to the fixing member  94  is weakened. Therefore, taking into consideration the reduction of the axial force, a design of increasing the fastening force or selecting a bolt having a thickness capable of withstanding the fastening force should be made, which increases the cost. 
         [0008]    The invention has been made to solve the above problem, and an object of the invention is to provide a steering device capable of suppressing an axial force of a fastening bolt from being reduced. 
       Solution to Problem 
       [0009]    In order to achieve the above object, a steering device of the invention has features of following (1) to (3). 
         [0010]    (1) A steering device comprising: 
         [0011]    a steering column that rotatably supports a steering shaft to which a steering wheel is connected; and 
         [0012]    a pair of support mechanisms that tiltably supports the steering column relative to a vehicle main body, 
         [0013]    wherein each of the support mechanisms includes: 
         [0014]    a support bracket having a column-side fastening part that is tiltably fastened to the steering column and a vehicle body-side fastening part that is fastened to a fixing member fixed to the vehicle main body; 
         [0015]    a fulcrum bolt that is inserted into an axle hole formed in the column-side fastening part, becomes a fulcrum upon tilting of the steering column and fastens the column-side fastening part to the steering column; and 
         [0016]    a bush that is interposed between the fulcrum bolt and the axle hole, 
         [0017]    wherein the vehicle body-side fastening part is formed with a fastening hole into which a fastening bolt for fastening the support bracket to the fixing member is inserted, 
         [0018]    wherein each of the support mechanisms includes an elastic member that is fitted to an outer periphery of an axle part of the fulcrum bolt, and is configured to oscillate relative to the steering column as the support bracket compresses the elastic member in an axial direction of the fulcrum bolt, and 
         [0019]    wherein the elastic member that is provided to at least one of the support mechanisms is formed so that the axle part is press-fitted thereto at a state before the column-side fastening part is fastened to the steering column. 
         [0020]    According to the above configuration (1), even when the fixing member is deviated from a normal position due to processing precision and the like, since the support bracket axially compresses the elastic member and oscillates relative to the steering column upon the fastening of the support bracket to the fixing member, it is possible to suppress the deformation of the support bracket. Also, at this time, since the elastic member is axially compressed, the support bracket can oscillate without deforming the flange part of the bush, unlike the related art. Therefore, it is possible to suppress an axial force of the fastening bolt from being reduced and it is not necessary to make a design reflecting the reduction of the axial force, so that it is possible to reduce the cost. In the above configuration, since the elastic member is formed so that the axle part of the fulcrum bolt is press-fitted thereto, it is difficult for the elastic member to separate from the axle part. Thereby, when mounting the support bracket, it is possible to prevent the elastic member from separating (coming out) from the axle part, thereby improving the mounting ability. 
         [0021]    (2) In the steering device described in the above (1), preferably, the axle part of the fulcrum bolt that is provided to at least one of the respective support mechanisms is formed to have an outer diameter larger than that of a screw part of the fulcrum bolt, and a connection end portion of the axle part with the screw part is tapered. 
         [0022]    According to the above configuration (2), since the connection end portion of the axle part is tapered, it is possible to easily press-fit the axle part to the elastic member, thereby further improving the mounting ability. 
         [0023]    (3) In the steering device described in the above (2), preferably, the fulcrum bolt is screwed into a screw hole formed in the steering column so as to fasten the column-side fastening part to the steering column, the elastic member that is provided to one of the support mechanisms is arranged between the column-side fastening part and the steering column, and the elastic member that is provided to the other of the support mechanisms is arranged between the column-side fastening part and a head part of the fulcrum bolt, the connection end portion of the fulcrum bolt that is provided to each support mechanism is tapered, and the screw hole of the steering column is formed at a surrounding thereof with a recess part into which the connection end portion of the fulcrum bolt provided to the other of the support mechanisms is inserted. 
         [0024]    According to the above configuration (3), since the elastic member that is provided to the one support mechanism is arranged between the column-side fastening part and the steering column, i.e., at a side of the column-side fastening part facing the steering column, the elastic member urges the steering column towards the other support mechanism. Also, since the elastic member that is provided to the other support mechanism is arranged between the column-side fastening part and the head part of the fulcrum bolt, i.e., at a side of the column-side fastening part opposite to the steering column, the elastic member urges the steering column towards the other support mechanism via the fulcrum bolt. That is, in the above configuration, the steering column is pressed towards the other support mechanism (support bracket). Hence, even when the respective members configuring the support mechanism are worn by the using over the long term and an axial gap is thus caused between the steering column and each support bracket, it is possible to suppress the steering column from rattling. 
         [0025]    Here, when the tapered connection end portion is arranged in the bush, the fulcrum bolt may rattle in the bush. In the above configuration, since the steering column is pressed towards the support bracket provided to the other support mechanism, the bush is arranged at the connection end portion-side of the axle part of the fulcrum bolt and the fulcrum bolt is apt to rattle in the other support mechanism. 
         [0026]    Regarding the above, according to the above configuration, since the connection end portion of the other fulcrum bolt is inserted into the recess part formed in the steering column, even when the connection end portion is tapered, the fulcrum bolt is difficult to rattle in the bush, so that the steering column can be stably supported. Thereby, while stably supporting the support bracket, it is possible to easily press-fit the axle part to the elastic member by tapering the connection end portions of each fulcrum bolt. 
       Advantageous Effect of Invention 
       [0027]    According to the invention, it is possible to provide a steering device capable of suppressing an axial force of a fastening bolt from being reduced. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0028]      FIG. 1  is a sectional view showing a vicinity of a steering column of a steering device according to an illustrative embodiment of the invention. 
           [0029]      FIG. 2  is a sectional view taken along a line A-A of  FIG. 1 . 
           [0030]      FIG. 3  is a sectional view taken along a line B-B of  FIG. 1 . 
           [0031]      FIG. 4  is an enlarged sectional view showing a vicinity of a first lower support mechanism of the illustrative embodiment. 
           [0032]      FIG. 5  is an enlarged sectional view showing a vicinity of a second lower support mechanism of the illustrative embodiment. 
           [0033]      FIG. 6  is a plan view of a coil spring of the illustrative embodiment. 
           [0034]      FIG. 7  illustrates an operation of the first lower support mechanism of the illustrative embodiment. 
           [0035]      FIG. 8  illustrates an operation of the second lower support mechanism of the illustrative embodiment. 
           [0036]      FIG. 9  is an enlarged sectional view of support mechanisms of the related art. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0037]    Hereinafter, an illustrative embodiment of the invention will be described with reference to the drawings. 
         [0038]    As shown in  FIG. 1 , in a steering device  1 , a column shaft  3  configuring a steering shaft  2  is rotatably accommodated in a steering column  5 . A steering wheel  6  is fixed to an end portion (a right end portion in  FIG. 1 ) of the column shaft  3  at a vehicle rear-side. In the meantime, an end portion (a left end portion in  FIG. 1 ) of the column shaft  3  at a vehicle front-side is connected with an intermediate shaft via a universal joint, which are not shown. Rotation and steering torque, which are accompanied by a steering operation, are transmitted to a steering mechanism such as rack and pinion mechanism and the like that changes a steering angle of the steering wheel. In the meantime, the steering shaft  2  is mounted to a vehicle with being inclined so that an end portion thereof at the vehicle front-side is positioned at a lower side in an upper-lower direction of the vehicle. 
         [0039]    Also, the steering device  1  is configured as an electric power steering device (EPS) of a so-called column assist-type that rotates the column shaft  3  while using a motor as a driving source. Specifically, as shown in  FIGS. 1 and 2 , the steering device  1  has an EPS actuator  12  that applies an assist force for assisting a steering operation to a steering system while using a motor  11  as a driving source. The motor  11  that is the driving source of the EPS actuator  12  is driving-connected to an output axle  14 , which configures a part of the column shaft  3 , via a deceleration mechanism  13 . In the meantime, the deceleration mechanism  13  is configured by engaging a worm wheel  15  connected to the output axle  14  and a worm axle  16  connected to the motor  11  with each other. The deceleration mechanism  13  and the output axle  14  are accommodated in a housing  17  that configures a part of the steering column  5 . 
         [0040]    Specifically, as shown in  FIG. 2 , the motor  11  is fixed to the housing  17  so that a motor axis is orthogonal to the output axle  14 . Also, the worm axle  16  connected to the motor  11  has both ends that are rotatably supported by bearings  18   a ,  18   b  provided in the housing  17  and is engaged with the worm wheel  15  connected to the output axle  14 . As shown in  FIG. 1 , the output axle  14  is rotatably supported by bearings  19   a  to  19   c  provided in the housing  17 . The EPS actuator  12  is configured to decelerate the rotation of the motor  11  by the deceleration mechanism  13  and to transmit the decelerated rotation to the output axle  14 , thereby applying the assist force to the steering system. 
         [0041]    Also, the steering device  1  has a telescopic function capable of adjusting a front-rear position of the steering wheel  6  (an axial steering position of the steering shaft  2 ). Specifically, the column shaft  3  of this illustrative embodiment has a first axle  21  having a hollow shape to which the steering wheel  6  is fixed and which configures the end portion of the column shaft  3  facing the steering wheel  6  and a second axle  22  that is spline-fitted to the first axle  21  and can be thus axially moved relative to the first axle  21 . The column shaft  3  is configured by connecting the output axle  14  to the second axle  22  connected to the first axle  21 . In the meantime, the output axle  14  is configured by connecting an upper shaft  14   a , which is connected to the second axle, and a lower shaft  14   b , to which the worm wheel  15  is fixed and which is connected to the intermediate shaft, via a torsion bar  14   c.    
         [0042]    In the meantime, the steering column  5  of this illustrative embodiment has an outer tube  24  that accommodates the first axle  21  via a bearing  23  and an inner tube  25  that accommodates the second axle  22 . The inner tube  25  is inserted into an inner periphery of the outer tube  24 , so that the outer tube can be axially slid relative to the inner tube  25 . The steering column  5  is configured by connecting the housing  17 , which accommodates therein the EPS actuator  12 , to the inner tube  25  connected to the outer tube  24 . The steering device  1  configured as described above has a configuration where an axial steering position thereof can be adjusted by moving the outer tube  24  and the first axle  21  relative to the inner tube  25  and the second axle  22 . 
         [0043]    Also, the steering device  1  has a tilt function of enabling a height position of the steering wheel  6  (a steering position in the upper-lower direction of the vehicle) to be adjusted. Specifically, as shown in  FIGS. 1 to 3 , the steering column  5  is tiltably supported to the vehicle main body by an upper support mechanism  26  and a pair of first and second lower support mechanisms  27 ,  28 . By tilting the column shaft  3  together with the steering column  5 , the steering position in the upper-lower direction of the vehicle can be adjusted. 
         [0044]    As shown in  FIG. 3 , the upper support mechanism  26  has a vehicle body-side bracket  31  that is fixed to a fixing member  29  fixed to the vehicle main body, a column-side bracket  32  to which the steering column  5  (outer tube  24 ) is fixed and a support axle  33  that connects the vehicle body-side bracket  31  and the column-side bracket  32  with each other. 
         [0045]    The vehicle body-side bracket  31  has a clamp  35  having a substantial U shape, when seen from the axial direction of the steering shaft  2 , and a flat plate-shaped plate  36  that is fixed to an upper end of the clamp  35 . A pair of side plate parts  35   a  that is provided to the clamp  35  is formed with substantially arc-shaped tilt long holes  37  along the tilt direction of the steering column  5 , respectively. A nut  40  is screwed to a fastening bolt  39  inserted into a fastening hole  38  of the plate  36 , so that the vehicle body-side bracket  31  is fastened to the fixing member  29 . 
         [0046]    The column-side bracket  32  has a substantial U shape, when seen from the axial direction of the steering shaft  2 , and the side plate parts  32   a  provided to the column-side bracket  32  are formed with telescopic long holes  41  along the axial direction, respectively. 
         [0047]    The support axle  33  has an axle shape and is formed at a base end-side (a left side in  FIG. 3 ) with a disc-shaped head part  42 . The support axle  33  is inserted into the tilt long holes  37  and the telescopic long holes  41  with the column-side bracket  32  being arranged at the inside of the vehicle body-side bracket  31  and the nut  43  is screwed to a leading end-side thereof (a right side in  FIG. 3 ), so that the support axle connects the vehicle body-side bracket  31  and the column-side bracket  32  with each other. Thereby, the column-side bracket  32  can be tilted relative to the vehicle body-side bracket  31  about fulcrum bolts  53 ,  73  provided to the first and second lower support mechanisms  27 ,  28  within a formation range of the tilt long holes  37  and can be moved along the axial direction of the column shaft  3  within a formation range of the telescopic long holes  41 . That is, the steering column  5  is supported by the upper support mechanism  26  so that it can be tilted relative to the fixing member  29  and can be axially moved within the above ranges. 
         [0048]    In the meantime, the upper support mechanism  26  is provided with a lock mechanism  44  that holds a position of the steering wheel  6  by operating an operation lever (not shown), which rotates the support axle  33 , to thus frictionally engage the respective side plate parts  32   a ,  35   a  each other. 
         [0049]    As shown in  FIG. 2 , the first and second lower support mechanisms  27 ,  28  that are the support mechanisms are respectively arranged at both sides of the steering column  5  in the left-right direction of the vehicle (the left-right direction in  FIG. 2 ). Specifically, the first lower support mechanism  27  is arranged at the right side of the steering column  5  with the worm axle  16  being positioned between the column shaft  3  and the first lower support mechanism and the second lower support mechanism  28  is arranged at the left side of the steering column  5 . 
         [0050]    The first and second lower support mechanisms  27 ,  28  have support brackets  51 ,  71  that connect the fixing member  45  fixed to the vehicle main body and the steering wheel  5  with each other, fulcrum bolts  53 ,  73  that are inserted into axle holes  52 ,  72  formed in the support brackets  51 ,  71  and bushes  54 ,  74  that are interposed between the axle holes  52 ,  72  and the fulcrum bolts  53 ,  73 , respectively. In the meantime, since the first and second lower support mechanisms  27 ,  28  are respectively configured by the same members, the respective members of the first lower support mechanism  27  are described and the respective members of the second lower support mechanism  28  are denoted only with the reference numerals in the parentheses. 
         [0051]    As shown in  FIG. 2 , the support bracket  51  ( 71 ) has a flat plate-shaped column-side fastening part  55  ( 75 ) having the axle hole  52  formed therein and a vehicle body-side fastening part  56  ( 76 ) extending from an end portion of the column-side fastening part  55  ( 75 ) in an orthogonal direction and has a substantial L shape. In the meantime, an end portion (a lower end portion in  FIG. 2 ) of the column-side fastening part  55  ( 75 ), which is at an opposite side to the vehicle body-side fastening part  56  ( 76 ), is formed with a limit part  57  ( 77 ) that is provided at an interval in the front-rear direction of the vehicle between the end portion and the housing  17 . The limit part  57  ( 77 ) is engaged to the housing  17 , so that the support bracket  51  ( 71 ) is suppressed from rotating about the fulcrum bolt  53  ( 73 ) beyond a predetermined range. 
         [0052]    As shown in  FIG. 4  ( 5 ), the fulcrum bolt  53  ( 73 ) has a screw part  58  ( 78 ) that is screwed into a screw hole  17   a  formed in the housing  17 , an axle part  59  ( 79 ) on which the bush  54  ( 74 ) is fitted and a head part  60  ( 80 ) that has an outer diameter larger than an inner diameter of the axle hole  52  ( 72 ) and holds the column-side fastening part  55  ( 75 ) between the steering column  5  and the head part. The bush  54  ( 74 ) has a cylindrical part  61  ( 81 ) into which the axle part  59  ( 79 ) of the fulcrum bolt  53  ( 73 ) is rotatably inserted and a disc-shaped flange part  62  ( 82 ) that extends from both ends of the cylindrical part  61  ( 81 ) in a diametrically outer direction. Meanwhile, in this illustrative embodiment, the bush  54  ( 74 ) is configured by coating a resin material having an excellent sliding ability on a metal mesh becoming a base material. 
         [0053]    As shown in  FIG. 2 , the vehicle body-side fastening part  56  ( 76 ) is formed with a fastening hole  64  ( 84 ) into which a fastening bolt  63  ( 83 ) fixed to the fixing member  45  is inserted. A nut  65  ( 85 ) is screwed onto the fastening bolt  63  ( 83 ) inserted into the fastening hole  64  ( 84 ), so that the support bracket  51  ( 71 ) is fastened to the fixing member  45 . Also, the fulcrum bolt  53  ( 73 ) inserted into the axle hole  52  ( 72 ) via the bush  54  ( 74 ) is screwed into the screw hole  17   a  of the housing  17 , so that the support bracket  51  ( 71 ) is fastened to the steering column  5 . Thereby, the steering column  5  is supported so that it can be tilted about the fulcrum bolt  53  ( 73 ) (tilt fulcrum) relative to the support bracket  51  ( 71 ) fixed to the vehicle main body. 
         [0054]    (Axial Force Reduction-Suppression Structure) 
         [0055]    In the below, an axial force reduction-suppression structure that suppresses the axial force of the fastening bolt for fastening the support bracket to the fixing member from being reduced is described. 
         [0056]    As described above, the fixing member  45  is deviated from a normal position (a position in a case where there is no processing error and the like) due to processing precision, mounting precision and the like, so that a fastening surface  54   a  facing the vehicle body-side fastening parts  56 ,  76  becomes non-parallel with (is inclined to) fastening surfaces  56   a ,  76   a  facing the fixing member  45  of the vehicle body-side fastening parts  56 ,  76  located at the normal position (refer to  FIG. 9 ). In this case, when fastening the support brackets  51 ,  71  to the fixing member  45 , the axial force of the fastening bolts  63 ,  83  is consumed so as to deform the support brackets  51 ,  71 . As a result, the fastening force of the support brackets  51 ,  71  to the fixing member  45  by the fastening bolts  63 ,  83  is weakened. 
         [0057]    Considering the above, as shown in  FIG. 2 , the first and second lower support mechanisms  27 ,  28  have coil springs  66 ,  86 , respectively, each of which is an elastic member that can be compressed in the axial direction of the fulcrum bolts  53 ,  73  (the left-right direction in  FIG. 2 ). Meanwhile, in this illustrative embodiment, as the coil springs  66 ,  86 , a so-called coiled wave spring is adopted which is formed by winding a band-shaped spring material into a coil shape and is bent into a wave shape continuing along a longitudinal direction of the spring material. The respective support brackets  51 ,  71  compress the coil springs  66 ,  86 , so that the first and second lower support mechanisms  27 ,  28  can oscillate relative to the steering column  5 . 
         [0058]    Specifically, as shown in  FIG. 4 , the coil spring  66  of the first lower support mechanism  27  is arranged at a side of the column-side fastening part  55  facing the steering column  5  and is held between the column-side fastening part  55  and the steering column  5  with being fitted to the outer periphery of the axle part  59 . In the meantime, a disc-shaped spacer  67  is interposed between the flange part  62  of the bush  54  and the coil spring  66 . 
         [0059]    In the meantime, as shown in  FIG. 5 , the coil spring  86  of the second lower support mechanism  28  is arranged at a side of the column-side fastening part  75  opposite to the steering column  5  and is held between the column-side fastening part  75  and the head part  80  of the fulcrum bolt  73  with being fitted to the outer periphery of the axle part  79 . In the meantime, a disc-shaped spacer  87  is interposed between the flange part  82  of the bush  74  and the coil spring  86 . Thereby, the steering column  5  is urged towards the second lower support mechanism  28  by the coil spring  66  and is urged towards the second lower support mechanism  28  via the fulcrum bolt  73  by the coil spring  86 , so that it is pressed towards the support bracket  71  provided to the second lower support mechanism  28 . 
         [0060]    Here, when the axle parts  59 ,  79  of the fulcrum bolts  53 ,  73  are mounted to the coil springs  66 ,  86  without being press-fitted, the coil springs  66 ,  86  are apt to be separated from the axle parts  59 ,  79  upon the mounting of the support brackets  51 ,  71 , so that the mounting ability is deteriorated. Considering this point, the coil springs  66 ,  86  are formed so that the axle parts  59 ,  79  are press-fitted thereto at a state before the coil springs are compressed (before the support brackets  51 ,  71  are fastened to the steering column  5 ). Also, the coil springs  66 ,  86  are compressed to expand in the diametrically outer direction (the diameters thereof are enlarged). Thereby, the column-side fastening parts  55 ,  75  are fastened to the steering column  5 , so that the coil springs are not press-fitted as regards the axle parts  59 ,  79 . 
         [0061]    Specifically, as shown in  FIG. 6 , the coil spring  66  has, when seen from the axial direction thereof, a main body part  66   a  that is formed by winding a band-shaped spring material along a true circle having an inner diameter slightly larger than an outer diameter of the axle part  59  and a press-fitting part  66   b  that is wound along an ellipse. In this illustrative embodiment, a long axis of the ellipse configured by the press-fitting part  66   b  is substantially the same as an inner diameter of the main body part  66   a  and a short axis thereof is smaller than the outer diameter of the axle part  59 . In the meantime, the press-fitting part  66   b  is formed over a substantially half circumference length from a winding start end portion and a winding completion end portion. Also, the press-fitting part  66   b  is formed so that as the coil spring  66  is compressed to expand in the diametrically outer direction, a short diameter of the press-fitting part becomes larger than the outer diameter of the axle part  59 . 
         [0062]    Likewise, the coil spring  86  has a main body part  86   a  that is wound into a true circle shape and a press-fitting part  86   b  that is wound into an elliptical shape. Before the compression, the coil spring is press-fitted to the axle part  79  and the column-side fastening part  75  is fastened to the steering column  5  by the fulcrum bolt  73  and thus compressed, so that the coil spring is not press-fitted as regards the axle part  79 . 
         [0063]    As shown in  FIG. 4 , the outer diameter of the axle part  59  is larger than that of the screw part  58 , and a connection end portion  59   a  of the axle part  59  with the screw part  58  is tapered. In the meantime, the connection end portion  59   a  is formed so that a leading end thereof has an inner diameter smaller than the short axis of the press-fitting part  66   b . The connection end portion  59   a  is inserted into a recess part  68  that is formed in the steering column  5 . Specifically, the steering column  5  is formed with a disc-shaped protrusion  69  that is arranged on the same axis as the screw hole  17   a  and has an inner diameter slightly larger than the outer diameter of the axle part  59 , and the recess part  68  is formed by the protrusion  69 . Also, the inner diameter of the protrusion  69  is smaller than the outer diameter of the coil spring  66  and a leading end of the protrusion  69  abuts on the coil spring  66 , so that the coil spring  66  is not inserted into the recess part  68 . Hence, in this illustrative embodiment, the protrusion  69  corresponds to a peripheral edge of the recess part  68 . 
         [0064]    By the above configuration, as shown in  FIG. 5 , the outer diameter of the axle part  79  is formed to be larger than that of the screw part  79  and a connection end portion  79   a  of the axle part  79  with the screw part  78  is tapered. The connection end portion  79   a  is inserted into a recess part  88  that is configured by an annular protrusion  89  formed at the steering column  5 . Also, a leading end of the protrusion  89  abuts on the flange part  82  of the bush  74 . 
         [0065]    The recess parts  68 ,  88  are formed to have the same depth (a length in the left-right direction in  FIGS. 4 and 5 ). Also, the column-side fastening parts  55 ,  75  have the same thickness, and the fulcrum bolts  53 ,  73 , the bushes  54 ,  74 , the coil springs  66 ,  86  and the spacers  67 ,  87  have the same shapes, respectively. Thereby, a compression amount of the coil spring  66  between the column-side fastening part  55  and the protrusion  69  of the steering column  5  and a compression amount of the coil spring  86  between the column-side fastening part  75  and the head part  80  of the fulcrum bolt  73  are the same, and set loads of the respective coil springs  66 ,  86  are the same. In the meantime, each of the coil spring  66 ,  86  is set with a set load capable of sufficiently suppressing the steering column  5  from rattling due to the applied reverse input and the like. 
         [0066]    As shown in  FIG. 7 , the first lower support mechanism  27  configured as described above is adapted to oscillate relative to the steering column  5  as the support bracket  51  axially compresses the coil spring  66 . Likewise, as shown in  FIG. 8 , the second lower support mechanism  28  is adapted to oscillate relative to the steering column  5  as the support bracket  71  axially compresses the coil spring  86 . Meanwhile, at this time, only the cylindrical parts  61 ,  81  of the bushes  54 ,  74  are deformed between the fulcrum bolts  53 ,  73  and the column-side fastening parts  55 ,  75  and the flange parts  62 ,  82  are not deformed. Also, in  FIGS. 7 and 8 , a state is shown with the dashed-dotted line in which the support brackets  51 ,  71  are oscillated in the plane orthogonal to the fastening surfaces  56   a ,  76   a  of the vehicle-side fastening parts  56 ,  76 , about contact points serving as fulcrums O 1 , O 2  at which the sides of the column-side fastening parts  55 ,  75  facing the vehicle body-side fastening parts  56 ,  76  contact the head parts  60 ,  80  of the fulcrum bolts  53 ,  73 , and a state is also shown with the dashed-two dotted line in which the support brackets  51 ,  71  are oscillated about contact points serving as fulcrums O 3 , O 4  at which the sides of the column-side fastening parts  55 ,  75  opposite to the vehicle body-side fastening parts  56 ,  76  contact the head parts  60 ,  80  of the fulcrum bolts  53 ,  73 . 
         [0067]    As described above, according to the illustrative embodiment, following effects can be obtained. 
         [0068]    (1) The pair of first and second lower support mechanisms  27 ,  28  has the coil springs  66 ,  86 , which are fitted to the outer peripheries of the axle parts  59 ,  79  of the fulcrum bolts  53 ,  73 , respectively, and oscillates relative to the steering column  5  as the support brackets  51 ,  71  compress the coil springs  66 ,  86 . The coil springs  66 ,  86  are formed so that the axle parts  59 ,  79  are press-fitted thereto at the state the before the column-side fastening parts  55 ,  75  are fastened to the steering column  5 . 
         [0069]    According to the above configuration, even when the fastening surface  45   a  of the fixing member  45  is deviated from the normal position due to the processing precision and the like, the support brackets  51 ,  71  axially compress the coil springs  66 ,  86  and oscillate upon the fastening of the support brackets  51 ,  71  to the fixing member  45  so that the fastening surfaces  56   a ,  76   a  of the vehicle body-side fastening parts  56 ,  76  are closely contacted to the fastening surface  45   a  of the fixing member  45 . Thereby, it is possible to suppress the deformation of the support brackets  51 ,  71 . Also, at this time, since the coil springs  66 ,  86  are axially compressed, it is possible to enable the support brackets  51 ,  71  to oscillate without deforming the flange parts  62 ,  82  of the cylindrical parts  61 ,  81  of the bushes  54 ,  74 , unlike the related art. Therefore, it is possible to suppress the axial force of the fastening bolts  63 ,  83  from being reduced and it is not necessary to make a design reflecting the reduction of the axial force, so that it is possible to reduce the cost. In the above configuration, since the coil springs  66 ,  86  are formed so that the axle parts  59 ,  79  are press-fitted thereto, it is difficult for the coil springs  66 ,  86  to separate from the axle parts  59 ,  79 . Thereby, when mounting the first and second lower support mechanisms  27 ,  28 , it is possible to prevent the coil springs  66 ,  86  from separating (coming out) from the axle parts  59 ,  79 , thereby improving the mounting ability. 
         [0070]    (2) The connection end portions  59   a ,  79   a  of the axle parts  59 ,  79  of the fulcrum bolts  53 ,  73  with the screw parts  58 ,  78  are tapered. Hence, it is possible to easily press-fit the axle parts  59 ,  79  into the coil springs  66 ,  86  and the bushes  54 ,  74 , thereby further improving the mounting ability. Furthermore, even when the winding start end portion and winding completion end portion of the coil spring  66  are formed with the press-fitting part  66   b , it is possible to prevent the fulcrum bolt  53  of the first lower support mechanism  27  from holding the press-fitting part  66   b  of the coil spring  66  between the protrusion  69  and the fulcrum bolt. 
         [0071]    (3) The fulcrum bolts  53 ,  73  are screwed into the screw hole  17   a  formed in the steering column  5 , so that the column-side fastening parts  55 ,  75  are fastened to the steering column  5 . Also, the coil spring  66  of the first lower support mechanism  27  is arranged between the column-side fastening part  55  and the steering column  5  and the coil spring  86  of the second lower support mechanism  28  is arranged between the column-side fastening part  75  and the head part  80  of the fulcrum bolt  73 . The steering column  5  is formed with the recess part  68  into which the connection end portion  59   a  of the fulcrum bolt  53  is inserted. 
         [0072]    According to the above configuration, the steering column  5  is pressed towards the support bracket  71  that is provided to the second lower support mechanism  28 . Hence, even when the respective members configuring the first and second lower support mechanisms  27 ,  28  are worn by the using over the long term and an axial gap is thus caused between the steering column  5  and the support brackets  51 ,  71 , it is possible to suppress the steering column  5  from rattling. 
         [0073]    Here, when the tapered connection end portions  59   a ,  79   a  are arranged in the bushes  54 ,  74 , the fulcrum bolts  53 ,  73  may rattle in the bushes  54 ,  74 . In the above configuration, since the steering column  5  is pressed towards the support bracket  71 , the bush  74  is arranged at the connection end portion  79   a -side of the axle part  79  of the fulcrum bolt  73  and the fulcrum bolt  73  is apt to rattle in the second lower support mechanism  28 . 
         [0074]    Regarding the above, according to the above configuration, since the connection end portion  79   a  of the fulcrum bolt  73  is inserted into the recess part  88  formed in the steering column  5 , even when the connection end portion  79   a  is tapered, the fulcrum bolt  73  is difficult to rattle in the bush  74 , so that the steering column  5  can be stably supported. Thereby, while stably supporting the support brackets  51 ,  71 , it is possible to easily press-fit the axle parts  59 ,  79  to the coil springs  66 ,  86  by tapering the connection end portions  59   a ,  79   a  of the respective fulcrum bolts  53 ,  73 . 
         [0075]    (4) The coil spring  66  abuts on the peripheral edge (protrusion  69 ) of the recess part  68  and the recess part  68  is formed to have the same depth as that of the recess part  88  into which the connection end portion  79   a  of the fulcrum bolt  73  is inserted. The column-side fastening parts  55 ,  75  are formed to have the same thickness, and the members (the fulcrum bolts  53 ,  73 , the bushes  54 ,  74 , the coil springs  66 ,  86  and the spacers  67 ,  87 ) configuring the first and second lower support mechanisms  27 ,  28  are formed to have the same shapes, respectively. 
         [0076]    Here, in the second lower support mechanism  28 , the coil spring  86  is held between the column-side fastening part  75  and the head part  80  of the fulcrum bolt  73 . Therefore, when the recess part  88  is formed, the compression amount of the coil spring  86  is increased as the depth of the recess part  88 . In this regard, according to the above configuration, since the coil spring  66  abuts on the peripheral edge of the recess part  68  in the first lower support mechanism  27 , too, the compression amount of the coil spring  66  is increased as the depth of the recess part  68 . 
         [0077]    In this regard, according to the above configuration, since the respective recess parts  68 ,  88  have the same depth, the column-side fastening parts  55 ,  75  have the same thickness and the members configuring the first and second lower support mechanisms  27 ,  28  have the same shapes, respectively, the compression amounts (set loads) of the coil springs  66 ,  86  are the same. Thereby, the members configuring the first and second lower support mechanisms  27 ,  28  can be commonalized to reduce the cost, and the set loads of the coil springs  66 ,  86  are made to be the same, so that the steering column  5  can be stably supported. 
         [0078]    (5) The coil springs  66 ,  86  are formed so that the axle parts  59 ,  79  are not press-fitted thereto at the state where the column-side fastening parts  55 ,  75  are fastened to the steering column  5 . Therefore, compared to a configuration where the axle parts  59 ,  79  are press-fitted to the coil springs at the state where the column-side fastening parts  55 ,  75  are fastened to the steering column  5 , the coil springs  66 ,  86  can stably urge the steering column  5 , so that it is possible to securely suppress the steering column  5  from rattling due to the applied reverse input and the like. 
         [0079]    In the meantime, the above illustrative embodiment can be appropriately changed and implemented as follows. 
         [0080]    In the above illustrative embodiment, as shown in  FIG. 2 , the shape of the support bracket  51  and the shape of the support bracket  71  are different from each other. However, the invention is not limited thereto. That is, the support brackets  51 ,  71  may be made to have the same shape. 
         [0081]    in the above illustrative embodiment, the column-side fastening parts  55 ,  75  are fastened to the steering column  5  and compressed, so that the axle parts  59 ,  79  are not press-fitted to the coil springs  66 ,  86 . However, the invention is not limited thereto. For example, the coil springs may be formed so that the axle parts  59 ,  79  are press-fitted thereto. 
         [0082]    In the above illustrative embodiment, the connection end portions  59   a ,  79   a  of the axle parts  59 ,  79  of the fulcrum bolts  53 ,  73  are tapered. However, the invention is not limited thereto. For example, only one of the connection end portions  59   a ,  79   a  may be tapered. Also, the axle parts  59 ,  79  may be formed to have constant diameters, respectively. 
         [0083]    In the above illustrative embodiment, the steering column  5  is formed with the recess parts  68 ,  88  into which the connection end portions  59   a ,  79   a  are inserted. However, the invention is not limited thereto. For example, the steering column  5  may be formed with only any one of the recess parts  68 ,  88 . Also, the steering column  5  may not be formed with the recess parts  68 ,  88 . 
         [0084]    In the above illustrative embodiment, the coil spring  66  of the first lower support mechanism  27  is arranged at the side of the column-side fastening part  55  facing the steering column  5  and the coil spring  86  of the second lower support mechanism  28  is arranged at the side of the column-side fastening part  55  opposite to the steering column  5 . However, the invention is not limited thereto. For example, the coil spring  66  may be arranged at the side of the column-side fastening part  55  opposite to the steering column  5  and the coil spring  86  may be arranged at the side of the column-side fastening part  55  facing the steering column  5 . Also, both the coil springs  66 ,  86  may be arranged at the side of the column-side fastening part  55  facing the steering column  5  or opposite to the steering column  5 . 
         [0085]    In the above illustrative embodiment, the axle parts  59 ,  79  are respectively press-fitted to the coil springs  66 ,  86  before the compression. However, the invention is not limited thereto. For example, only the coil spring  66  may be formed so that the axle part  59  is press-fitted thereto. Also, only the coil spring  86  may be formed so that the axle part  79  is press-fitted thereto. 
         [0086]    In the above illustrative embodiment, the press-fitting parts  66   b ,  86   b  of the coil springs  66 ,  86  are formed over the substantially half circumference length from the winding start end portion and the winding completion end portion. However, the invention is not limited thereto. For example, the coil springs  66 ,  86  may be formed so that the entire become the press-fitting parts  66   b ,  86   b.    
         [0087]    In the above illustrative embodiment, the coiled wave springs are adopted as the coil springs  66 ,  86  serving as the elastic members. However, a typical coil spring in which a spring material extends along a spiral direction may be adopted. Also, the invention is not limited to the coil spring. For example, a disc spring may be adopted as the elastic member insomuch as the axle parts  59 ,  79  of the fulcrum bolts  53 ,  73  are press-fitted thereto. 
         [0088]    In the above illustrative embodiment, the bushes  54 ,  74  are configured by coating the resin material to the metal mesh becoming the base material. However, the invention is not limited thereto. For example, the bushes may be made of only the resin material. Also, the bushes  54 ,  74  may be made of materials other than the resin material insomuch as the support brackets  51 ,  71  can oscillate. 
         [0089]    In the above illustrative embodiment, the column-side fastening parts  55 ,  75  are fastened to the steering column  5  by the fulcrum bolts  53 ,  73  that are inserted from both sides in the left-right direction of the vehicle. However, the invention is not limited thereto. For example, the fulcrum bolts  53 ,  73  may be provided so that the screw parts  58 ,  78  of the fulcrum bolts  53 ,  73  protrude from the inside of the steering column  5  towards both sides in the left-right direction of the vehicle and the nuts may be screwed to the screw parts  58 ,  78 , thereby fastening the column-side fastening parts  55 ,  75  to the steering column  5 . 
         [0090]    In the above illustrative embodiment, the invention is applied to the steering device having the tilt and telescopic functions. However, the invention is not limited thereto. For example, the invention may be applied to a steering device having only a tilt adjusting function. 
         [0091]    In the above illustrative embodiment, the steering device  1  is configured as the electric power steering device (EPS) of a so-called column assist type that applies the assist force to the output axle  14  configuring the column shaft  3 . However, the invention is not limited thereto. For example, the invention may be applied to an EPS other than the column assist type, such as a so-called lock assist type, a hydraulic power steering device or a steering device of a non-assist type. 
         [0092]    In the below, the technical spirits that can be perceived from the above illustrative embodiment and separate examples are described together with the effects thereof. 
         [0093]    (A) In the steering device described in the above (3), the recess part is formed so that the elastic member abuts on the peripheral edge of the recess part, and is formed to have the same depth as that of the recess part to which the connection end portion of the fulcrum bolt provided to the one side is inserted. 
         [0094]    Here, in the other support mechanism, the elastic member is held between the column-side fastening part and the head part of the fulcrum bolt. Hence, when the steering column is formed with the recess part, the compression amount of the elastic member is increased as the depth of the recess part. In this regard, in the above configuration, since the elastic member abuts on the peripheral edge of the recess part in the one support mechanism, too, the compression amount of the elastic member is increased as the depth of the recess part. Since the depths of the respective recess parts are the same, the compression amounts (set loads) of the respective elastic members are made to be the same by making the thicknesses of the support brackets (column-side fastening parts) of the respective support mechanisms same and commonalizing the members (fulcrum bolts, elastic members) configuring the respective support mechanisms. Therefore, the members configuring the respective support mechanisms are commonalized to reduce the cost, and the set loads of the elastic members are made to be the same, so that the steering column can be stably supported. 
         [0095]    (B) In the steering device described in any one of (1) to (3) and (A), the elastic member is the coil spring and the elastic member is formed so that the axle part is not press-fitted thereto at a state where the column-side fastening part is fastened to the steering column. 
         [0096]    That is, the coil spring has a property that it is compressed to expand in the diametrically outer direction (the inner diameter thereof is enlarged). Considering this, in the above configuration, the elastic member is formed so that as it is compressed upon the fastening of the column-side fastening part to the steering column, the axle part is not press-fitted to the elastic member. Hence, compared to a configuration where the axle part is press-fitted to the elastic member at the state where the column-side fastening part is fastened to the steering column, the coil spring can stably urge the steering column, so that it is possible to suppress the steering column from rattling due to the applied reverse input and the like. 
         [0097]    Although the invention has been specifically described with reference to the specific illustrative embodiment, it is apparent to one skilled in the art that a variety of changes and modifications can be made without departing from the spirit and scope of the invention. 
         [0098]    This application is based on Japanese Patent Application No. 2011-001471 filed on Jan. 6, 2011, the disclosures of which are incorporated herein by way of reference. 
       INDUSTRIAL APPLICABILITY 
       [0099]    According to the invention, it is possible to a steering device capable of suppressing an axial force of a fastening bolt from being reduced. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               1 : steering device 
               2 : steering shaft 
               5 : steering column 
               6 : steering wheel 
               17   a : screw hole 
               29 ,  45 : fixing member 
               45   a ,  56   a ,  76   a : fastening surface 
               51 ,  71 : support bracket 
               52 ,  72 : axle hole 
               53 ,  73 : fulcrum bolt 
               54 ,  74 : bush 
               55 ,  75 : column-side fastening part 
               56 ,  76 : vehicle body-side fastening part 
               57 ,  77 : limit part 
               58 ,  78 : screw part 
               59 ,  79 : axle part 
               59   a ,  79   a : connection end portion 
               60 ,  80 : head part 
               61 ,  81 : cylindrical part 
               62 ,  82 : flange part 
               63 ,  83 : fastening bolt 
               64 ,  84 : fastening hole 
               65 ,  85 : nut 
               66 ,  86 : coil spring 
               66   a ,  86   a : main body part 
               66   b ,  86   b : press-fitting part 
               67 ,  87 : spacer 
               68 ,  88 : recess part 
               69 ,  89 : protrusion 
             O 1 , O 2 , O 3 , O 4 : fulcrum