Patent Publication Number: US-2023150451-A1

Title: Steering column device

Description:
TECHNICAL FIELD 
     The present disclosure relates to a steering column device including a lock mechanism that restricts rotation of a steering shaft. 
     BACKGROUND ART 
     Steering column devices are provided with a lock mechanism that prevents the steering wheel from rotating to prevent automobile theft. In the lock mechanism, when an ignition key is set to a lock position and a key is pulled out, a lock key on the steering column side engages with a key lock collar mounted on the outer periphery of a steering shaft and is locked. 
     However, if the steering wheel is forced to rotate with a strong force while the steering shaft is locked, the lock key may be broken and the function of the lock mechanism may be lost, thereby impairing the function as an antitheft device. Thus, there is a known steering device in which, when a large torque is applied, the steering shaft slips and rotates with respect to the key lock collar while receiving a frictional force (slip torque), thereby preventing the lock key from being broken (see Patent Literature 1). 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2007-153093 
     BRIEF SUMMARY 
     It is necessary to set the above-described frictional force generated between the outer peripheral surface of the steering shaft and the inner peripheral surface of the key lock collar to an appropriate value that is insufficient to destroy the lock key in the locked state but does not interfere with the steering operation in the unlocked state. 
     Thus, it is an object of the present disclosure to implement an appropriate frictional force generated between the outer peripheral surface of the steering shaft and the inner peripheral surface of the key lock collar. 
     A steering column device according to an aspect of the present disclosure includes a shaft support member in a cylindrical shape provided on a vehicle body side, and a steering shaft rotatably provided inside the shaft support member. The steering column device includes a key lock collar mounted on an outer peripheral surface of the steering shaft, the outer peripheral surface facing the shaft support member, the key lock collar including a plurality of concave parts each extending in an axial direction on an outer peripheral part thereof and a plurality of convex parts formed between the concave parts along a circumferential direction. The steering column device includes a lock key provided on the shaft support member and restricting rotation of the steering shaft with respect to the shaft support member by making a tip part thereof engage with the concave parts of the key lock collar. The key lock collar includes a key lock collar body including the plurality of concave parts and the plurality of convex parts, and a cylindrical portion provided adjacent in the axial direction to the key lock collar body, and an outer diameter of the cylindrical portion is smaller than an outer diameter of a circle including tip surfaces of the plurality of convex parts and larger than an outer diameter of a circle including outside surfaces of the plurality of concave parts. 
     The present disclosure makes it possible to implement an appropriate frictional force generated between the outer peripheral surface of the steering shaft and the inner peripheral surface of the key lock collar. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a left side view of a steering column device according to an embodiment. 
         FIG.  2    is a side view of a key lock collar used in the steering column device in FIG.  1 . 
         FIG.  3    is a left side view of  FIG.  2   . 
         FIG.  4    is a right side view of  FIG.  2   . 
         FIG.  5    is an exploded perspective view including a steering shaft and a tolerance ring on which the key lock collar in  FIG.  2    is mounted. 
         FIG.  6    is an assembly diagram illustrating the key lock collar, the steering shaft, and the tolerance ring in  FIG.  5   . 
         FIG.  7    is a cross-sectional view of a portion corresponding to the key lock collar in  FIG.  6   , along the axis. 
         FIG.  8    is a cross-sectional view of a key lock collar according to another embodiment. 
         FIG.  9    is a cross-sectional view of a key lock collar according to yet another embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments according to the present disclosure are described below with reference to the drawings. Note that in the drawings, the front of the vehicle is indicated by an arrow FR, and the rear of the vehicle is indicated by an arrow RR. 
     As illustrated in  FIG.  1   , a steering column device  1  includes two front and rear vehicle body mounting brackets  2  and  3  for fixing to a vehicle body. An outer column  5  is supported by the vehicle body mounting brackets  2 ,  3  to be freely swingable (freely adjustable in tilt position) in the vertical direction of the vehicle body. An inner column  7  is supported by the outer column  5  to be freely movable (freely adjustable in telescopic position) in the longitudinal direction of the vehicle body. 
     A lock portion  9  tightens and locks the vehicle body mounting bracket  3 , the outer column  5 , and the inner column  7  by an operation lever  10  being pushed up and unlocks them by the operation lever  10  being pushed down. The tilt position or the telescopic position is adjusted when the lock portion  9  is in the unlocked state, and the tilt position or the telescopic position is fixed by setting the lock portion  9  in the locked state after the adjustment. 
     A steering shaft  11  is rotatably supported in the inner column  7  and the outer column  5  through a pair of front and rear bearings  13 F and  13 R. A steering wheel, which is not illustrated, is mounted on the rear end of the steering shaft  11 . The steering shaft  11  includes a lower shaft  11 L housed in the outer column  5  and an upper shaft  11 U housed in the inner column  7 . 
     By connecting the upper shaft  11 U and the lower shaft  11 L with a spline, the upper shaft  11 U and the lower shaft  11 L rotate as one body on an axis with respect to the outer column  5  and the inner column  7 . In the axial direction, the upper shaft  11 U is movable relative to the lower shaft  11 L. That is, at the time of the telescopic position adjustment described above, the inner column  7  and the upper shaft  11 U move as one body forward and backward with respect to the outer column  5  and the lower shaft  11 L. 
     A key lock collar  15  having a cylindrical shape as a whole is mounted on the outer peripheral surface of the lower shaft  11 L. The key lock collar  15  is between the front bearing  13 F and the front end of the upper shaft  11 U and is closer to the bearing  13 F than the front end of the upper shaft  11 U, at a position facing the inner peripheral surface of the outer column  5 . The key lock collar  15  is made from a metal material having elasticity such as carbon steel for mechanical structures. 
     A lock key  17  that is engaged with the key lock collar  15  is movably mounted on the outer column  5  toward the axis of the key lock collar  15 . When a key is pulled out with an ignition key in a lock position, the front end of the lock key  17  is engaged with and locked to the key lock collar  15 . The engagement of the lock key  17  with the key lock collar  15  restricts the rotation of the steering shaft  11  with respect to the outer column  5 . Thus, the lock mechanism including the key lock collar  15  and the lock key  17  functions as an antitheft device. The outer column  5  constitutes a cylindrical shaft support member provided on the vehicle body side. Note that the lock key  17  in  FIG.  1    is positioned at the lower part for ease of understanding, but is not limited to the position in  FIG.  1    and is provided at an optimum position in the circumferential direction. 
     Next, the key lock collar  15  is described with reference to  FIGS.  2  to  7   . 
     The key lock collar  15  includes a key lock collar body  19  occupying most of the key lock collar  15  in the axial direction, and a cylindrical portion  21  provided adjacent in the axial direction to the key lock collar body  19 . The cylindrical portion  21  is positioned closer to the rear of the vehicle body than the key lock collar body  19  and is shorter in the axial direction than the key lock collar body  19 . The key lock collar body  19  includes concave parts  19   a  and convex parts  19   b  alternately formed on the outer peripheral part along the circumferential direction. That is, each convex part  19   b  is formed between two concave parts  19   a . The concave parts  19   a  and the convex parts  19   b  extend along the axial direction and are each formed at equal intervals along the circumferential direction. 
     As illustrated in  FIGS.  3  and  4   , an outer diameter D 1  of the cylindrical portion  21  is smaller than an outer diameter D 2  of the convex parts  19   b  and larger than an outer diameter D 3  of the concave part  19   a  (D 2 &gt;D 1 &gt;D 3 ). The key lock collar  15  has an inner diameter D 4 , which is constant in the whole axial direction over the key lock collar body  19  and the cylindrical portion  21 . Note that the outer diameter D 2  of the convex parts  19   b  corresponds to the diameter of a circle P including the tip surfaces of the convex parts  19   b , and the outer diameter D 3  of the concave parts  19   a  corresponds to the diameter of a circle Q including the outer surfaces of the concave parts  19   a.    
     In the key lock collar  15 , the concave parts  19   a  and the convex parts  19   b  are formed on the outer peripheral surface through plastic working (cold forging) in which a mold is pushed into a cylindrical material having circular outer and inner peripheral surfaces. Specifically, while the material is set in one die with one end in the axial direction open, the other die having multiple press-in convex parts for forming the concave parts  19   a  on the inner peripheral surface of the cylindrical portion along the circumferential direction is moved along the axial direction. When the press-in convex parts move to draw the outer peripheral surface of the material along the axial direction to form the concave parts  19   a , the excess wall generated in the drawing becomes a part of the cylindrical portion  21 . After the plastic working, finish processing is appropriately performed on the key lock collar  15  to have a desired shape as a whole. 
     The inner diameter D 4  of the key lock collar  15  is formed slightly larger than the outer diameter of the lower shaft  11 L, and a tolerance ring  23  in a substantially cylindrical shape is provided between the key lock collar  15  and the lower shaft  11 L. The tolerance ring  23  is formed by bending an elastically deformable belt-shaped metal plate into an approximate C-shape, and a spring-shaped part  23   a  made from a concavo-convex part is formed on the inner and outer peripheral surfaces. 
     The tolerance ring  23  is elastically deformed radially outward while being assembled between the key lock collar  15  and the lower shaft  11 L. The spring-shaped portion  23   a  of the tolerance ring  23  is compressed between the key lock collar  15  and the lower shaft  11 L, thereby generating a frictional force (slip torque) F between the key lock collar  15  and the lower shaft  11 L. As illustrated in  FIG.  7   , the tolerance ring  23  has an axial length slightly shorter than that of the key lock collar  15  but may be equal. 
     When the lock key  17  enters the concave parts  19   a  of the key lock collar  15 , the steering shaft  11  is locked and its rotation is restricted, resulting in a locked state. When the steering shaft  11  in the locked state is forcibly rotated by a strong force, the steering shaft  1 I slides and rotates while receiving the frictional force F against the key lock collar  15  to prevent the breakage of the lock key  17 . 
     It is necessary to set the frictional force F here appropriately. That is, if the frictional force F is larger than an appropriate value, the lock key  17  in the locked state is broken, and if it is smaller than the appropriate value, the steering shaft  11  is easily rotated in spite of being locked. In other words, the frictional force F needs to be insufficient to destroy the lock key  17  but to be large enough to enable the steering operation necessary for driving the automobile. 
     The tolerance ring  23  illustrated in  FIG.  5    is inserted into the key lock collar  15  as illustrated in  FIG.  6    while being assembled to the lower shaft  11 L. In the tolerance ring  23  after insertion, the spring-shaped portion  23   a  may be positioned to face both the key lock collar body  19  and the cylindrical portion  21  as illustrated in  FIG.  7   . In this case, if the outer diameter D 1  of the cylindrical portion  21  is equal to the outer diameter D 2  of the convex parts  19   b , and if the axial length of the cylindrical portion  21  is also equal to that of the key lock collar body  19 , the rigidity of the cylindrical portion  21  is higher than that of the key lock collar body  19 . Since the concave parts  19   a  are formed on the key lock collar body  19 , the rigidity thereof tends to be lower than that of the cylindrical portion  21 . 
     In this state, when the tolerance ring  23  is assembled between the lower shaft  11 L and the key lock collar  15 , the amounts of elastic deformation of the tolerance ring  23  are different between a portion facing the cylindrical portion  21  (referred to as a cylinder facing part below) having high rigidity and a portion facing the key lock collar body  19  (referred to as a body facing part below) having low rigidity. If the elastic deformation amounts are different, the above-described frictional force F changes between the cylindrical portion  21  and the key lock collar body  19 , and a stable frictional force F cannot be obtained. 
     Then, in the present embodiment, the rigidity of the cylindrical portion  21  is adjusted by changing the outer diameter of the cylindrical portion  21 , and the frictional force F is made substantially uniform at the cylindrical portion  21  and at the key lock collar body  19 . Specifically, as described above, the outer diameter D 1  of the cylindrical portion  21  is made smaller than the outer diameter D 2  of the convex parts  19   b  and larger than the outer diameter D 3  of the concave parts  19   a . The cylindrical portion  21  and the key lock collar body  19  have the same inner diameter D 4 . Thus, the cylindrical portion  21  is thinner than a part thereof corresponding to the convex parts  19   b  and thicker than a part thereof corresponding to the concave parts  19   a  in thickness. 
     As described above, adjusting the outer diameter of the cylindrical portion  21  enables the rigidity of the cylindrical portion  21  to be made close to that of the key lock collar body  19 , and the rigidity of the cylindrical portion  21  and the rigidity of the key lock collar body  19  to be made substantially uniform. Thus, the elastic deformation amounts of the tolerance ring  23  at the time of assembly are substantially equal at the cylinder facing part and at the body facing part. Consequently, the frictional force F is made substantially uniform at the cylindrical portion  21  and at the key lock collar body  19 , thereby providing a stable frictional force F. 
     Note that the difference in rigidity between the cylindrical portion  21  and the key lock collar body  19  is also influenced by the axial length of each part. In the present embodiment, the cylindrical portion  21  is shorter than the key lock collar body  19  in the axial length. Thus, adjusting the axial length of the cylindrical portion  21  within the above-described range of the length setting provides the rigidity in consideration of the axial length for the cylindrical portion  21 . 
     In the present embodiment, the frictional force F is adjusted through changing the shape of the cylindrical portion  21 . Thus, when the frictional force F is adjusted, even when the inner diameter D 4  of the key lock collar  15 , the outer diameter D 3  of the part corresponding to the concave parts  19   a , or the like cannot be changed due to the structure of the other parts, the adjustment can be easily performed. 
     In the present embodiment, the tolerance ring  23  is provided between the key lock collar  15  and the steering shaft  11 . Thus, even when the frictional force F is generated using the tolerance ring  23 , the frictional force F can be made substantially uniform along the axial direction through adjusting the outer diameter, the axial length, and the like of the cylindrical portion  21  so that the rigidity of the cylindrical portion  21  and the key lock collar body  19  is substantially uniform. 
     In the key lock collar  15  in the present embodiment, the axial length of the cylindrical portion  21  is set shorter than that of the key lock collar body  19 . When the axial lengths of the cylindrical portion  21  and the key lock collar body  19  are equal to each other, the key lock collar body  19  has lower rigidity than the cylindrical portion  21  because the concave parts  19   a  are formed thereon. 
     Thus, shortening the cylindrical portion  21  in the axial direction, which tends to be higher in rigidity than the key lock collar body  19 , which tends to be lower in rigidity, enables the rigidity of the cylindrical portion  21  and the rigidity of the key lock collar body  19  to be made substantially equal. Consequently, the elastic deformation amounts of the tolerance ring  23  at the time of assembly are substantially equal at the cylinder facing part and at the body facing part, and the frictional force F is made substantially uniform at the cylindrical portion  21  and at the key lock collar body  19 , thereby providing a stable frictional force F. 
     Note that the difference in rigidity between the cylindrical portion  21  and the key lock collar body  19  is also influenced by the thickness of each part. In the present embodiment, the cylindrical portion  21  is made thinner than the part corresponding to the convex parts  19   b  and thicker than the part corresponding to the concave parts  19   a . Thus, adjusting the thickness of the cylindrical portion  21  in the above-described range of thickness setting provides the rigidity in consideration of thickness. 
     Next, other embodiments are described with reference to  FIGS.  8  and  9   . 
     In the embodiments illustrated in  FIGS.  8  and  9   , each cylindrical portion  21  of key lock collars  15 A and  15 B has a thickness that is made non-uniform. Thus, the rigidity of the cylindrical portion  21  is adjusted so that the rigidity of the cylindrical portion  21  and the rigidity of the key lock collar body  19  are substantially equal to each other. Consequently, the elastic deformation amounts of the tolerance ring  23  at the time of assembly are substantially equal at the cylinder facing part and at the body facing part, and the frictional force F is made substantially uniform at the cylindrical portion  21  and at the key lock collar body  19 , thereby providing a stable frictional force F. 
     In the embodiments illustrated in  FIGS.  8  and  9   , each cylindrical portion  21  of the key lock collars  15 A and  15 B is made thinner at a part thereof opposite to a part thereof adjacent to the key lock collar body  19  than the part thereof adjacent to the key lock collar body  19 . Thus, the rigidity of the cylindrical portion  21  is adjusted so that the rigidity of the cylindrical portion  21  and the rigidity of the key lock collar body  19  are substantially equal to each other. Consequently, the elastic deformation amounts of the tolerance ring  23  at the time of assembly are substantially equal at the cylinder facing part and at the body facing part, and the frictional force F is made substantially uniform at the cylindrical portion  21  and at the key lock collar body  19 , thereby providing a stable frictional force F. 
     In the embodiments illustrated in  FIGS.  8  and  9   , the thickness of each cylindrical portion  21  of the key lock collars  15 A and  15 B gradually decreases from the side adjacent to the key lock collar body  19  toward the side opposite to the side adjacent to the key lock collar body  19 . Thus, the rigidity of the cylindrical portion  21  is adjusted so that the rigidity of the cylindrical portion  21  and the rigidity of the key lock collar body  19  are substantially equal to each other. Consequently, the elastic deformation amounts of the tolerance ring  23  at the time of assembly are substantially equal at the cylinder facing part and at the body facing part, and the frictional force F is made substantially uniform at the cylindrical portion  21  and at the key lock collar body  19 , thereby providing a stable frictional force F. 
     In the key lock collar  15 A according to the embodiment illustrated in  FIG.  8   , the outer peripheral surface of an end part  21   a  of the cylindrical portion  21  on the side opposite to the side adjacent to the key lock collar body  19  is defined as an inclined surface  21   b . The inclined surface  21   b  inclines so that its outer diameter becomes smaller toward the end part  21   a  than toward the key lock collar body  19 . The rigidity of the cylindrical portion  21  is adjusted through adjusting the inclination angle of the inclined surface  21   b , the inclination range in the axial direction, or the like, so that the rigidity of the cylindrical portion  21  and the rigidity of the key lock collar body  19  are substantially equal to each other. Consequently, the elastic deformation amounts of the tolerance ring  23  at the time of assembly are substantially equal at the cylinder facing part and at the body facing part, and the frictional force F is made substantially uniform at the cylindrical portion  21  and at the key lock collar body  19 , thereby providing a stable frictional force F. 
     In the key lock collar  15 B according to the embodiment illustrated in  FIG.  9   , the inner peripheral surface of the end part  21   a  of the cylindrical portion  21 , which is opposite to the side adjacent to the key lock collar body  19 , is defined as a step part  21   c  formed in a step shape along the central axis direction of the cylindrical portion  21 . The step part  21   c  is stepped to have the inner diameter larger toward the end part  21   a  than toward the key lock collar body  19 . The step part  21   c  illustrated in  FIG.  9    has two steps but may have one step or three or more steps. 
     The rigidity of the cylindrical portion  21  is adjusted through adjusting the number of steps in the step part  21   c , the step range in the axial direction, or the like, so that the rigidity of the cylindrical portion  21  and the rigidity of the key lock collar body  19  are substantially equal. Consequently, the elastic deformation amounts of the tolerance ring  23  at the time of assembly are substantially equal at the cylinder facing part and at the body facing part, and the frictional force F is made substantially uniform at the cylindrical portion  21  and at the key lock collar body  19 , thereby providing a stable frictional force F. 
     Although the embodiments according to the present disclosure have been described above, these embodiments are only illustrative to facilitate understanding of the present disclosure, and the present disclosure is not limited to these embodiments. The technical scope of the present disclosure is not limited to the specific technical matters disclosed in the above embodiments but also includes various variations, modifications, alternative techniques, and the like, which can be derived therefrom with ease. 
     For example, in the above-described embodiments, the key lock collar  15  is mounted on the outer peripheral surface of the lower shaft  11 L but may be mounted on the outer peripheral surface of the upper shaft  11 U. Here, for example, in  FIG.  1   , the key lock collar  15  is mounted at a position facing the inner peripheral surface of the inner column  7  (right side of the vehicle body mounting bracket  3  in  FIG.  1   ) at a portion where the upper shaft  11 U and the lower shaft  11 L are not connected by the spline. Thus, the lock key  17  that is engaged with the key lock collar  15  is mounted on the inner column  7 . Even when the key lock collar  15  is mounted on the upper shaft  11 U, the same action and effect are obtained as when it is mounted on the lower shaft  11 L. 
     The tolerance ring  23  according to the above-described embodiment is not limited to the C-shape in which a part in the circumferential direction is notched, and may be in a ring shape. 
     The tolerance ring  23  according to the above-described embodiment may not be used. In this case, the inner diameter D 4  of the key lock collar  15  before assembly is made slightly smaller than the outer diameter of the lower shaft  11 L. By press-fitting the lower shaft  11 L into the key lock collar  15 , the key lock collar  15  is elastically deformed, and the frictional force F is generated between the lower shaft  11 L and the key lock collar  15 . Note that chamfering the inner corner of the end part of the key lock collar  15  where the lower shaft  11 L is press-fitted facilitates the press-fitting work. 
     Here, as described above, adjusting the outer diameter D 1  of the cylindrical portion  21 , the axial length, or the like makes the rigidity of the cylindrical portion  21  substantially equal to that of the key lock collar body  19 . Consequently, the elastic deformation amounts of the key lock collar  15  when assembled are substantially equal at the cylindrical portion  21  and at the key lock collar body  19 , and the frictional force F is substantially uniform at a part corresponding to the cylindrical portion  21  and at a part corresponding to the key lock collar body  19 , thereby providing a stable frictional force F. 
     In the embodiment illustrated in  FIG.  8   , the inclined surface  21   b  is formed on the outer peripheral surface of the cylindrical portion  21 , but the inclined surface may be formed on the inner peripheral surface of the cylindrical portion  21  or may be formed on both the outer peripheral surface and the inner peripheral surface of the cylindrical portion  21 . In the embodiment illustrated in  FIG.  9   , the step part  21   c  is formed on the inner peripheral surface of the cylindrical portion  21 , but the step part may be formed on the outer peripheral surface of the cylindrical portion  21  or may be formed on both the outer peripheral surface and the inner peripheral surface of the cylindrical portion  21 . The inclined surface and the stepped part may be combined. For example, the inclined surface may be provided on the outer peripheral surface of the cylindrical portion  21 , and the step part may be provided on the inner peripheral surface of the cylindrical portion  21 . 
     For the configuration in which the thickness of the cylindrical portion  21  is non-uniform, a recessed part may be formed on at least one of the inner peripheral surface or the outer peripheral surface of the cylindrical portion  21  to provide a partially thin-walled part. Alternatively, at least one of the inner peripheral corner part or the outer peripheral corner part of the end part of the cylindrical portion  21 , which is opposite to the part adjacent to the key lock collar body  19 , may be chamfered. 
     REFERENCE SIGNS LIST 
     
         
         
           
               5  Outer column (shaft support member) 
               11  Steering shaft 
               15  Key lock collar 
               17  Lock key 
               19  Key lock collar body 
               19   a  Concave parts of key lock collar body 
               19   b  Convex parts of key lock collar body 
               21  Cylindrical portion of key lock collar 
               21   b  Inclined surface of cylindrical portion 
               23  Tolerance ring 
             D 1  Outer diameter of cylindrical portion 
             D 2  Outer diameter of convex parts 
             D 3  Outer diameter of concave parts 
             D 3  of the concave parts  19   a.