Abstract:
An object of the present invention is to markedly increase the tilt holding force of a tilt telescopic column. A tilt telescopic steering device includes: a fixed bracket  1  fixed to a vehicle; a movable bracket  2  capable of moving relative to the fixed bracket  1 ; an intermediate bracket  3  which movably supports the movable bracket  2  in an axial direction, is rotatably pivoted on the fixed bracket  1  and is provided with a bearing  301  for rotatably supporting a steering shaft  101 ; a lock shaft  4  for tiltably and telescopicably fixing the fixed bracket  1  and the movable bracket  2  at a predetermined position; and a connecting shaft  5  for telescopicably fixing the movable bracket  2  and the intermediate bracket  3.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a tilt telescopic steering device that allows significant enhancement of the tilt holding force of a tilt telescopic column. 
     2. Description of the Related Art 
     As examples of the background art, Japanese Patent Application Laid-open Nos. 2005-7905 and 2005-125994 describe steering devices comprising an ordinary tilt telescopic adjustment mechanism in which tilt and telescopic stroke are fixed by a lever at one site. 
     The features of Japanese Patent Application Laid-open No. 2005-7905 are analyzed next as a concrete example of the foregoing. During tilt in Japanese Patent Application Laid-open No. 2005-7905, a shaft rod member  23  act as a support shaft, while a shaft rod member  18  and a movable bracket  4  pivot along a tilt long hole, in the up-and-down direction relative to the a fixed bracket  3 . During a telescopic stroke, meanwhile, the movable bracket  4  is displaced relative to the shaft rod members  18 ,  23 , in a front-rear direction, via a telescopic long hole  17  of the movable bracket  4 . The rotation shaft for tilt is slidable during the telescopic stroke, but fixed during tilt. The shaft rod member  23 , moreover, is slidably provided, although it is fixed during driving travel. Tilt telescopic fixing (locking) is carried out at one site by way of a lever  20  mounted on the shaft rod member  18 . 
     In Japanese Patent Application Laid-open No. 2005-7905, having a tilt fulcrum A (center of rotation: shaft rod member  23 ), an action point B (lever fastening position: shaft rod member  18 ), and a force point C where the handle tilts, the force exerted on the force point C acts on the action point B (lever fastening position) with a high ratio. To increase the tilt holding force (force acting on the force point C) during lever fastening, therefore, it becomes necessary to increase the torque for fastening the lever at the action point B. Japanese Patent Application Laid-open No. 2005-125994 has the same problem. 
     SUMMARY OF THE INVENTION 
     In light of the foregoing, the problem (for instance, technical problem and purpose) to be solved by the invention is to realize a steering device in which the tilt holding force can be considerably enhanced during driving and steering, by distributing, over a plurality of sites, a force that is applied to a lever fastening position through a tilting movement of a tilt telescopic mechanism. 
     As a result of diligent research directed at solving the above problem, the invention of claim  1  solves the above problem by way of a tilt telescopic steering device, comprising a fixed bracket fixed to a vehicle; a movable bracket capable of moving relative to the fixed bracket; an intermediate bracket which movably supports the movable bracket in the axial direction, is rotatably pivoted on the fixed bracket and is provided with a bearing for rotatably supporting a steering shaft; a lock shaft for tiltably and telescopicably fixing the fixed bracket and the movable bracket at a predetermined position; and a connecting shaft for telescopicably fixing the movable bracket and the intermediate bracket. 
     The invention of claim  2  solves the above problem by way of the tilt telescopic steering device having the above features and wherein the telescopic adjustment part comprises a horizontal long hole formed in the movable bracket that is connected to the intermediate bracket via the connecting shaft inserted into the horizontal long hole. The invention of claim  3  solves the above problem by way of the tilt telescopic steering device having the above features and wherein the telescopic adjustment part comprises a horizontal long hole formed in the movable bracket that is connected to the intermediate bracket via the connecting shaft inserted into the horizontal long hole. 
     The invention of claim  4  solves the above problem by way of the tilt telescopic steering device having the above features and wherein the telescopic adjustment part comprises a horizontal long hole formed in the intermediate bracket, the connecting shaft being fastened to the horizontal long hole. The invention of claim  5  or  6  solves the above problem by way of the tilt telescopic steering device having the above features and wherein the fixed bracket and the movable bracket are fixed with the lock shaft at a predetermined position via a tilt adjustment hole and a telescopic adjustment hole. 
     Further, the invention of claim  7  or  8  solves the above problem by way of the tilt telescopic steering device having the above features and wherein the lock shaft is fastened and fixed with a lock bolt, and the connecting shaft is fastened and fixed with a fastening bolt via a bush. The invention of claim  9  or  10  solves the above problem by way of the tilt telescopic steering device having the above features and wherein the pivoting site of the intermediate bracket constitutes a tilt pivot. 
     The invention of claim  1  allows obtaining higher rigidity in a steering column, and allows considerably enhancing the tilt holding force of a tilt telescopic column. The inventions of claims  2  and  3  afford the same effect as the invention of claim  1 . The invention of claim  4  allows obtaining a yet more stable tilt holding force. The invention of claim  5  or  6  provides a simple constitution, while the invention of claim  7  or  8  allows obtaining a yet more stable tilt holding force. The invention of claim  9  or  10  allows obtaining an even yet more stable tilt holding force. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a side-view diagram of the present invention,  FIG. 1B  is a cross-sectional side-view diagram of a relevant portion of  FIG. 1A ; 
         FIG. 2  is a perspective-view diagram of the present invention; 
         FIG. 3  is an exploded side-view diagram of the main members of the present invention; 
         FIG. 4A  is a cross-sectional diagram of a relevant portion of the present invention,  FIG. 4B  is a front-view diagram of a fixed bracket,  FIG. 4C  is a cross-sectional diagram of an intermediate bracket,  FIG. 4D  is a cross-sectional diagram of a movable bracket; 
         FIG. 5A  is a perspective-view diagram of the intermediate bracket,  FIG. 5B  is a cross-sectional diagram of the telescopic configuration of the intermediate bracket and the movable bracket; 
         FIG. 6  is a cross-sectional diagram of  FIG. 1  along the arrow X-X; 
         FIG. 7A  is a schematic side-view diagram of a steering column in a raised state resulting from a tilt operation,  FIG. 7B  is a schematic side-view diagram of the steering column in a lowered state resulting from a tilt operation,  FIG. 7C  is schematic side-view diagram of the steering column extended towards the driver (rightwards) as a result of a telescopic operation,  FIG. 7D  is schematic side-view diagram of the steering column extended towards the engine (leftwards) as a result of a telescopic operation; 
         FIG. 8A  is a perspective-view diagram of another embodiment of the intermediate bracket,  FIG. 8B  is a perspective-view diagram of another embodiment of the movable bracket,  FIG. 8C  is a cross-sectional diagram of the telescopic configuration of the intermediate bracket and the movable bracket in another embodiment; and 
         FIG. 9A  is cross-sectional side-view diagram of a relevant portion of the present invention, and  FIG. 9B  is an enlarged cross-sectional diagram of a site of the steering shaft and the intermediate bracket in  FIG. 9A . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention are described next with reference to accompanying drawings. As illustrated in  FIGS. 1 to 3 , the present invention is a structure joined, or connected via various members, to a steering column  10 , for tilting and telescopically moving the steering column  10 . The main feature of the present invention comprises a fixed bracket  1 , a movable bracket  2 , an intermediate bracket  3 , a lock shaft  4  inserted through the fixed bracket  1  and the movable bracket  2  and fixed at a predetermined position, a telescopic adjustment part  6  and a connecting shaft  5  connected to the movable bracket  2  and the intermediate bracket  3 , a pivot shaft  7  for rotationally pivoting the fixed bracket  1  and the intermediate bracket  3 , a spring member  8 , and an operating lever  9 . 
     As illustrated in  FIG. 1A ,  FIG. 2 ,  FIG. 3 ,  FIGS. 4A and 4B , the fixed bracket  1  comprises a pair of left and right support side plates  11 ,  11  and a mounting top portion  12 . The mounting top portion  12 , which is attached at a predetermined position in the vehicle, for instance, via slide capsule members  14 ,  14  and so forth, has a structure such that it accommodates resistance while sliding at the mounting position, only during impacts such as collisions or the like, while absorbing the impact energy, and thereby softening the impact and protecting the driver from accidents. 
     As illustrated in  FIGS. 1A ,  FIG. 2 ,  FIG. 4D  and so forth, the movable bracket  2  has a substantially U-shaped cross section, and has formed, at a bottom  22  thereof, column supports  21 ,  21  at both sides in the width direction. The two column supports  21 ,  21  support and fix the steering column  10 . The two column supports  21 ,  21  are mounted, clamped by the lock shaft  4 , between the two support side plates  11 ,  11  of the fixed bracket  1  (see  FIG. 6 ). The fixed bracket  1  and the movable bracket  2  are connected via tilt adjustment holes  13 ,  13 , telescopic adjustment holes  23 ,  23  and the lock shaft  4 . The lock shaft  4  is coupled by being inserted through cams  401 ,  402 . The cams  401 ,  402  engage, thereby fixing the lock shaft  4 , when the operating lever  9  is brought to a horizontal attitude relative to the steering column  10 . 
     As illustrated in  FIG. 3 , the tilt adjustment holes  13 ,  13  are formed as vertical long holes at an appropriate position of the two support side plates  11 ,  11 . The vertical long hole  131  has an arcuate shape. That is, the long hole  131  is formed to a radial arcuate shape around the pivot shaft  7 . As illustrated in  FIG. 3 , the telescopic adjustment holes  23 ,  23  are formed as horizontal long holes  231 ,  231  at the ends of the movable bracket  2  in the longitudinal direction. The telescopic adjustment holes  23 ,  23  enable the tilting movement and the telescopic movement of the movable bracket  2  with respect to the fixed bracket  1 . The tilt adjustment hole  13 , as the vertical long hole long holes  131 , enables tilt adjustment, while the telescopic adjustment hole  23 , as the horizontal long hole  231 , enables telescopic adjustment. 
     The movable bracket  2  and the intermediate bracket  3  are connected via the telescopic adjustment parts  6 ,  6  and the connecting shaft  5  (see  FIG. 1 ,  FIG. 5B ). The telescopic adjustment parts  6 ,  6  are formed as horizontal long holes  61 ,  61  at the lower portion of the intermediate bracket  3 . A bush  601  is slidably fitted on each horizontal long hole  61 . The connecting shaft  5  is inserted through the bush  601 . The bush  601  enhances slidability by reducing looseness between the movable bracket  2  and the intermediate bracket  3 . The bush  601  enables the telescopic movement of the movable bracket  2  with respect to the intermediate bracket  3 . 
     As illustrated in  FIG. 8B , the telescopic adjustment part  6  is formed as horizontal long holes  62 ,  62  at the ends of the movable bracket  2  in the longitudinal direction. The connecting shaft  5  is provided in the intermediate bracket  3 , and thus the movable bracket  2 , need only perform a telescopic movement relative to the intermediate bracket  3 . The horizontal long holes  61 ,  62  that form the telescopic adjustment part  6  are not limited to being provided in the intermediate bracket  3  or the movable bracket  2 . 
     The fixed bracket  1  and the intermediate bracket  3  are configured so as to be rotatably supported by the pivot shaft  7 , as illustrated in  FIG. 1A  and  FIG. 4A . Specifically, the pivot shaft  7  constitutes a pivot  71  for tilting movement. As a result, the intermediate bracket  3  rotates relative to the fixed bracket  1  during the tilt operation, but remains fixed during a telescopic operation. 
     The movable bracket  2  and the intermediate bracket  3  are fastened and fixed with the connecting shaft  5 , by way of the telescopic adjustment parts  6 ,  6 . The connecting shaft  5  is located at the site at which sliding takes place. As illustrated in  FIG. 5A , the intermediate bracket  3  comprises the two support side plates  31 ,  31 , a bottom  32  between the two support side plates  31 ,  31 , at the lower portion of the latter, and an end bracket  33  between the two support side plates  31 ,  31 . A flange  302  of a bearing  301  that supports a steering shaft  101  is mounted on the lead end bracket  33  of the intermediate bracket  3 , via bolts and nuts (see  FIG. 9B ). 
     A fixing hook  34  for latching one end (lower end) of the spring member  8  is formed on one of the two support side plates  31 ,  31  of the intermediate bracket  3  (see  FIG. 1A ). The fixing hook  34  is attached to the support side plate  31 , for instance, through welding of another member (see  FIG. 8A ). The other end of the spring member  8  (upper end) is latched to an appropriate latching portion of the mounting top portion  12  of the fixed bracket  1 . The spring member  8  is provided here, specifically, as a tension coil spring  81 , but is not limited thereto. So long as it pulls the intermediate bracket  3  upwards, the spring member  8  may be configured as a torsion spring or the like. 
     The movement of the device will be explained next. During tilt operation, a steering wheel W (handle) is moved up and down to match the body of the driver. To that end, the fixed state of the lock shaft  4  is released by way of the operating lever  9  (clockwise rotation in  FIG. 1A ), to raise or lower thereby the steering column  10 . Specifically, the steering column  10 , the movable bracket  2  and the intermediate bracket  3  appropriately rotate around the pivot shaft  7 , as a fulcrum. The lock shaft  4  is then fixed by the operating lever  9  (counterclockwise rotation in  FIG. 1A ). 
     During telescopic operation, the steering wheel W (handle) is moved back and forth to adapt to the body of the driver. To that end, the operating lever  9  is released and the steering column  10  is moved back and forth. Specifically, the movable bracket  2  is moved back and forth, relative to the fixed bracket  1  and the intermediate bracket  3 , by way of the telescopic adjustment holes  23  and the telescopic adjustment parts  6 , with the pivot shaft  7  as a support. The lock shaft  4  is then fixed at a desired position by the operating lever  9 . This completes the tilt operation and the telescopic operation. The above tilt operation and telescopic operation are carried out in combination during adjustment of the steering column  10  to a good handle position suited to the body of the driver. 
     The movement during driving travel will be explained next. That is, ordinary driving travel takes place once the tilt operation and the telescopic operation are over. The forces acting in this case are depicted in, for instance,  FIG. 1A  and  FIG. 7 . The fulcrum (center of rotation) during the tilt operation or the telescopic operation of the steering column  10  and the steering wheel W is located at the pivot shaft  7 . Next, the driver holds the steering wheel W, which receives thereupon the load of the arms alone, although the weight of the driver may add partially to that load. 
     When in that situation a force is exerted on the lever fastening position, a force from the steering column  10  acts on the steering shaft  101 , in the tilt direction. Therefore, the structure for supporting this force is one part of the element that maintains the tilt holding force. In the present invention, the bearing  301  that supports the steering shaft  101  is mounted on the end bracket  33  of the intermediate bracket  3 , and hence the force acting on the steering shaft  101  in the tilt direction is sequentially supported by the steering column  10 , the movable bracket  2 , the fixed bracket  1  and the vehicle body, and, besides, by the bearing  301 , the intermediate bracket  3 , the fixed bracket  1  the vehicle body, in this order, and by the steering column  10 , the movable bracket  2 , the intermediate bracket  3 , the fixed bracket  1  and the vehicle body, in this order. As a result, the structure of the present invention, comprising the intermediate bracket  3  having the bearing  301  fixed thereto, affords a higher tilt holding force than in conventional art, where no intermediate bracket is provided.