Abstract:
The present invention relates to a steering lock device for antitheft of vehicle and aims to assure the safety of the steering lock device against secondary collision, on one hand, and to improve visual impression of peripheral domain of the steering column by closing an apertural areas for insertion of tilt lever operating knob with a cover of the steering lock device. 
     The steering lock device is provided a cover member with the buffering member interposed in order to surround the steering lock device and thereby to assure safety from the secondary collision. In addition, an insertion hole formed in the steering column for a knob used to control a tilt steering device is closed with the cover member.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a steering lock device adapted to lock steering operation for a vehicle. 
       BACKGROUND ART 
       [0002]    The conventional steering lock device for a vehicle adapted to lock steering operation for the antitheft purpose is provided on an outer peripheral surface of a steering shaft adapted to be rotated by steering operation with an engagement recess. 
         [0003]    In synchronization with response to operation of stopping the engine by a vehicle driver using a key or the other means, a to-and-fro movable lock bolt moves ahead into engagement with said engagement recess to restrict rotation of the steering shaft. In this way, the steering shaft is locked so that the steering operation can not be done. 
         [0004]    In synchronization with operation of starting the engine by the driver using the key, said lock bolt is moved back and disengaged from said engagement recess, releasing the steering shaft from the restriction. In this way, the steering shaft is unlocked so that the steering operation can be carried out. 
         [0005]    It will be appreciated that the engagement recess of the steering shaft is often out of alignment with a position at which the lock bolt is provided at a moment of advancing the lock bolt toward the steering shaft. 
         [0006]    In view of this problem, the conventional steering lock device is provided with biasing means adapted to bias the lock bolt to be moved forward. 
         [0007]    Incorporation of the biasing means allows the driver may rotate the steering shaft until the lock bolt is aligned with the engagement recess whereupon the lock bolt plunges into the engagement recess under the effect of the biasing means without need to start the engine by use of a key or the like in order to carry out operation of unlocking. 
         [0008]    One of the prior art documents relating to such steering lock device is Japanese Patent Application Laid-Open Publication No. 2005-343378. 
         [0009]    This PATENT DOCUMENT discloses a steering lock device provided with a cam mechanism adapted to actuate a lock bolt to move to a locked position or an unlocked position. 
         [0010]    In the case of this steering lock device of prior art, an electric motor actuating the lock bolt is fixed within a casing and the electric motor is power-supplied from the vehicle. 
         [0011]    Specifically, a connector on the vehicle side connected to a main microcomputer (ECU) loaded on the vehicle is electrically connected to a connector extending out from a casing of the steering lock device so that a control board power-supplied from this connector via a printed substrate and terminals causes the electric motor to be normally rotated or reversely rotated. 
         [0012]    In order to improve the antitheft effect, the steering lock device conventionally devises various countermeasures, for example, making the device not visible externally, making it difficult to operate the device directly, and enhancing a degree of freedom of layout for switching devices or the other components disposed around the steering column cover of the steering shaft by mounting the steering lock device to the lower portion of the steering shaft on the innermost side (the front side of vehicle) within the steering column cover. 
         [0013]    However, the high antitheft effect is required for such steering lock device as has been described above and the various components such the lock bolt and the electric motor are usually housed within the housing molded from zinc or the like hard material and the lower portion of the steering shaft lies immediately in front of and opposed to the knees of the driver sitting on the cab seat. 
         [0014]    When the driver is thrown forward by impact in the case of collision accident of the vehicle, there is a possibility of so-called secondary collision such that the driver&#39;s knees may burst through the steering column cover and collide the housing of the steering lock device. 
         [0015]    Within the steering column cover, the position-adjusting device (e.g., tilt steering device or telescopic steering device) is provided to adjust the position of the steering handle depending on the driver T s physical size or predilection. 
         [0016]    Similarly to the steering lock device, such position-adjusting device is also provided in the innermost side (the front side of the vehicle) with respect to the steering shaft. 
         [0017]    Particularly, the tilt lever for control of the tilt steering device (height-adjusting device) is supported on the side surface so as to extend outward from the interior of the steering column cover and the distal end of this lever is provided with the control knob which is bent so as to lie on the middle level of the steering column cover. 
         [0018]    The steering column cover comprises the upper cover and the lower cover and, after the tilt steering device has been attached to the steering shaft, the steering column cover is covered from above and below. Therefore, the bottom of the lower cover of the steering column cover must be formed with the opening through which the tilt lever of the tilt steering device and the control knob thereof can extend outward. 
         [0019]    Consequentially, various metallic parts such as the steering shaft and various metallic parts are visible externally, adversely affecting the appearance of the instrument panel of which the design is very important, and making the appearance unattractive. 
         [0020]    To solve this problem, various countermeasures have been implemented, for example, a cover has been separately provided to close the opening. 
         [0021]    In view of the problems as have been described above, it is a first object of the present invention to assure a safety from the secondary collision of the driver with the steering lock device and it is a second object of the present invention to close the opening of the steering column cover through the control knob of the tilt lever in order to improve visual quality of the peripheral region of the steering column. 
       SUMMARY OF THE INVENTION 
       [0022]    The first object set forth above is achieved, according to the invention, by an improvement in the steering lock device comprising a lock bolt adapted to be to-and-fro movable between a locked position at which the lock bolt is engaged with a steering shaft coupled to a steering wheel and an unlocked position at which such engagement is released, an actuator causing the lock bolt to move, a transmission mechanism adapted to transmit a driving force from the actuator to the lock bolt so as to move the lock bolt toward the locked position or the unlocked position, and a housing with a cover adapted to house at least the lock bolt, said actuator and the transmission mechanism. The improvement according to the invention is characterized in that a cover member adapted to cover side walls and a bottom of the housing, and an elastic buffering member provided between the cover member and the housing. 
         [0023]    The second object set forth above is achieved, according to the invention, by an improvement in the steering lock device characterized in that the device further comprises a steering column pipe rotatably supporting the steering shaft, a position-adjusting device adapted to position-adjusting the steering shaft in a vertical direction of the steering column pipe, a control lever provided at one end with a control knob adapted to be operated so as to switch the position-adjusting device between a position-adjustable state and a position-nonadjustable state in a selective manner, a steering column cover integrally attached to the steering shaft so as to cover the steering shaft, the position-adjusting device and the control lever, a control lever insertion hole and a control knob insertion hole provided in the bottom of the steering column cover, and the control knob insertion hole is closed with the cover member of the steering lock device mounted on the steering shaft. 
         [0024]    In the steering lock device of the aforementioned construction, the housing made of hard material is provided on its outer peripheral surface with the elastic buffering member so that, even if the driver&#39;s knees collide with the steering lock device by a shock due to the vehicle&#39;s collision accident, the buffering member may sufficiently alleviate a collision shock to protect the driver from a serious damage and to assure the safety against the secondary collision. 
         [0025]    Furthermore, the buffering member covering the space for the lock mechanism within the housing is effective also to absorb the sound generated within the steering lock device and leaking externally when the lock bolt is actuated by the electric motor. 
         [0026]    In addition to the advantages as have been described above, the unique construction of the steering lock device according to the invention such that the opening formed in the steering column cover for passage of the control knob of the position-adjusting device is closed with the cover member for the steering lock device makes it unnecessary to prepare a separate cover member in order to close the opening formed in the steering column cover for passage of the control knob. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  is a sectional view showing the steering lock device according to an embodiment of the present invention is a locked position. 
           [0028]      FIG. 2  is an exploded perspective view of the lock device and the bracket. 
           [0029]      FIG. 3  is a perspective view of the lock device together with the cover member mounted thereon. 
           [0030]      FIG. 4  is an exploded perspective view of the lock device and the cover member. 
           [0031]      FIG. 5  is a perspective view showing, partially in a sectional view, the lock device mounted on the steering shaft. 
           [0032]      FIG. 6  is a sectional view taken along a line  6 - 6  in  FIG. 5 . 
           [0033]      FIG. 7  is a bottom view of the steering column cover before the lock device is mounted on the steering shaft. 
           [0034]      FIG. 8  is a bottom view of the steering column cover after the lock device has been mounted on the steering shaft. 
           [0035]      FIG. 9(   a ) is a partially scale-enlarged view showing the slide engagement pit formed in the outer column tube of the steering shaft and  FIG. 9(   b ) is a sectional view taken along a line  9   b - 9   b  in  FIG. 9(   a ) and  FIG. 9(   c ) is a sectional view of the protuberance of the lock device taken along a line  9   c - 9   c  in  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]    Details of the steering lock device will be more fully understood from the description of the embodiment given hereunder in reference with the accompanying drawings. 
         [0037]      FIGS. 1 through 4  illustrate the steering lock device  1  (referred to hereinafter simply as “lock device”). 
         [0038]    As will be appreciated from  FIG. 5  through  FIG. 9 , this lock device  1  is disposed around a steering shaft  2  adapted to be rotated in synchronization with operation of rotating a steering handle (not shown) and operates in association with operation of a push switch or user&#39;s card key (both not shown) used for starting or stoppage of an engine or the like. 
         [0039]    As shown by  FIG. 6 , the steering shaft  2  is formed at predetermined level in an axial direction on its peripheral surface with a plurality of engagement recesses  3  at regular intervals in a circumferential direction. 
         [0040]    As will be apparent from  FIG. 1 , the lock device  1  according to this embodiment includes an one side open housing  10  and a housing cover  25  and comprises, within this, a lock bolt  34 , an electric motor  46  serving as an actuator, a transmission mechanism and an auxiliary lock mechanism  57  adapted to control a to-and-fro movement of the lock bolt  34 . 
         [0041]    The lock device further includes a control board  70  adapted to control the electric motor  46  on the based on an actual position of the lock bolt  34 . 
         [0042]    The housing  10  is provided in the form of one side opened rectangular container molded from metallic material such as zinc and having therein a space  11  for the control board  70  on one side and a space  16  for the lock mechanism on the other side. 
         [0043]    The space  11  for control board is adapted to house the electric motor  46  and the control board  70  serving to control the electric motor  46 . To this end, the space  11  is formed with a cavity  12  in conformity to a contour of the electric motor  46 . 
         [0044]    The space  11  for the control board is further provided with bosses (not shown) used to screw clamp a motor cover  47  and thereby to position the electric motor  46  and bosses (not shown) used to screw clamp a housing cover  25 . 
         [0045]    The space  11  for the control board is further provided on the side wall opposed to the space  16  for the lock mechanism with a notch  15  in which an outer end surface  72   a  of an electric connector  72  is exposed. 
         [0046]    The space  16  for the lock mechanism is adapted to contain the lock bolt  34  and the transmission mechanism and has a protuberance extending in a direction opposed to the open side. 
         [0047]    This protuberance  17  is provided with a lock bolt insertion hole  18  extending therethrough along a direction in which the housing cover  25  is mounted. 
         [0048]    In the space  16  for the lock mechanism, there is further provided around the lock bolt insertion hole  18  with a first supporting protuberance  19  annularly extending inward and rotatably supporting a rotator member  49  which will be described later. 
         [0049]    According to this embodiment, as shown by  FIGS. 2 through 4  and  FIG. 9(   a ), an upper surface (i.e., upper side as viewed in  FIG. 2)  of the protuberance  17  formed with the lock bolt insertion hole  18  has a substantially trapezoidal cross-section defined by a slope extending from the side of a front surface  16   a  (i.e., right side as viewed in  FIG. 2 ) of the space  16  for lock mechanism of the housing  10  toward the side of a rear surface  16   b  (i.e., left side as viewed in  FIG. 2 ), in which the connector  72  of the control board  70  is exposed, of the space  11  for the control board. 
         [0050]    Opposite sloped side walls of the protuberance  17  are formed fully along the slope with slide grooves  17   a  and the upper surface of the protuberance  17  are formed just above these slide grooves  17   a  with collars  17   b.    
         [0051]    Opposite side surfaces of the housing  10  defined in a lower part (i.e., lower side as viewed in  FIG. 2 ) of this protuberance  17  are formed with laterally extending convex portions  17   c  which are, in turn, formed with screw-insertion holes  17   d  used to secure outer column tubes  4  of the steering shaft  2 , which will be described later, with bolts  170 . 
         [0052]    An upper surface of the space  11  for the control board defined at a level lower than the protuberance  17  of the space  16  for the lock mechanism of the housing  10  is provided, as shown by  FIG. 2 , with two threaded holes  10   c  associated with two screw-insertion holes  112   a  of a bracket  110  which will be described later, a positioning rib  10   b  projecting from the upper surface of the cavity  12  housing the electric motor  46  and a positioning rib  10   a  horizontally projecting from a joint between a side surface of the protuberance  18  and the upper surface of the cavity  12 . 
         [0053]    The threaded holes  10   c  are formed so as to protuberate to the same level of the upper surface of the cavity  12 . 
         [0054]    As will be apparent from  FIG. 1 , the protuberance  17  of the space  16  for the lock mechanism is formed with a through-hole  20  extending in parallel to the lock bolt insertion hole  18  in the direction along which the housing cover  25  is mounted. 
         [0055]    This through-hole communicates with a space for an auxiliary lock mechanism  57  which is concaved inward from the outer surface of the protuberance  17 . 
         [0056]    The auxiliary lock mechanism  57  is to restrict to-and-fro movement of the lock bolt in the situation of the housing  10  for the lock device  1  having been disassembled (destroyed) and thereby to prevent illicit unlocking. However, the auxiliary lock mechanism has no direct relationship with the present invention and therefore details thereof will not be described herein. 
         [0057]    The housing cover  25  is used to close the open side of the housing  10  and may be secured to the housing  10  by threadably engaging screws or the like with bosses (not shown) projecting from the inner walls of the housing  10 . 
         [0058]    The housing cover  25  has a convex wall  27  extending into the notch  15 . 
         [0059]    This convex wall  27  partially closes the notch  15 . 
         [0060]    In this way, the notch  15  cooperates with the convex wall  27  to define an opening  73  through which the outer end surface  72   a  of the connector  72  is exposed. 
         [0061]    The outer end surface  72   a  of the connector  72  is surrounded by an edge  15   a  of the notch  15  of the housing  10  and an edge  27   a  of the convex wall  27  of the housing cover  25 . 
         [0062]    At a position properly opposed to the first supporting protuberance  19  provided in the space  16  of the lock mechanism, there is provided a second annular supporting protuberance  28  which rotatably supports the other end of the rotator member  49 . 
         [0063]    This second supporting protuberance  28  is provided on its inner peripheral surface with a plurality of lock bolt guide grooves  29  at regular intervals in the circumferential direction. 
         [0064]    The housing cover  25  includes a locking prong  32  formed integrally therewith so as to extend through the through-hole  20  of the housing  10  into engagement with the auxiliary lock mechanism  57  in its inactive state and thereby to keep the auxiliary lock mechanism in its inactive state relative to the lock bolt  34 . 
         [0065]    A plate-like bracket  110  is adapted to be integrally attached to the upper surface of the space  11  for the control board and provided with positioning grooves  115   a,    115   b  operatively associated with the positioning ribs  10   a,    10   b  of the space  11  for the control board, respectively, and a pair of threaded through-holes  112   a  adapted to receive respective fixing bolts  180 . 
         [0066]    The bracket  110  serves to mount a cover member  100  which will be described later to the housing  10  and, as shown by  FIGS. 2 and 4 , the bracket  110  is provided with a pair of through-holes  111   a  adapted to receive respective bosses  103  of the cover member  100  and a pair of screw-insertion holes  112   b  operatively associated with threaded holes  104  of the cover member  100 . 
         [0067]    The bracket  110  includes a pair of wings  113   a,    113   b  horizontally and vertically extending from opposite ends of a body of the bracket  110 , respectively. 
         [0068]    Another boss receiving through-hole  111   b  provided in the horizontally extending wing  113   a  is adapted to receive a mounting boss (not shown) of a steering column cover  150  and to mount this steering column cover  150  to the lock device  1 . 
         [0069]    The vertically extending wing  113   b  is provided with a substantially oval opening  114  to which a clip (not shown) is mounted. The clip serves to hold a harness of a switching device provided within the steering column cover  150 . 
         [0070]    As will be appreciated from the foregoing description, the bracket  110  may have auxiliary functions in addition to its primary function to secure the cover member  100 , which will be described later more in detail, to the lock device  1 . 
         [0071]    The lock bolt  34  is configured in the form of a square pillar as shown by  FIGS. 1 and 6  and dimensioned to be inserted into the lock bolt insertion hole  18 . The lock bolt  34  has its upper end in the form of an engagement convex  35  adapted to be properly associated with the engagement recess  3  of the steering shaft  2 . 
         [0072]    The lock bolt  34  is to-and-fro driven by the electric motor  46  via the transmission mechanism between the locked position at which the lock bolt  34  is engaged with the engagement recess  3  provided on the side of the steering shaft  2  and the unlocked position at which the lock bolt  34  is disengaged from the engagement recess  3  of the steering shaft  2 . 
         [0073]    If the engagement convex  35  is out of alignment with the engagement recess  3  in the circumferential direction when it is desired to bring the engagement convex  35  into engagement with the engagement recess  3 , the spring  44  continues to bias the lock bolt  34  to move forward until the engagement recess  3  is aligned with the engagement convex  35  of the lock bolt  34  and, upon alignment, the lock bolt  34  is plunged forward into the engagement recess  3  to effectuate the desired engagement. 
         [0074]    According to this embodiment, the lock bolt  34  is to-and-fro driven by the intermediary of a separately provided cam member  39  and, to this end, the lock bolt  34  is provided on its lower portion with a protuberance  36  by which the cam member  39  is coupled to the lock bolt  34 . 
         [0075]    This coupling protuberance  36  presents a rectangular cross-section is provided with a coupling hole  37  extending through this protuberance  36  orthogonally to the axial direction between opposed walls of the protuberance  36 . 
         [0076]    The lock bolt  34  is further provided with a notch  38  opposed to the space into which the auxiliary lock member is inserted when the engagement convex  35  is engaged with the engagement recess  3  of the steering shaft  2 . 
         [0077]    The cam member  39  has a substantially cylindrical shape having its lower portion disposed within the second supporting protuberance  28  of the housing cover  25  and its upper portion disposed within a rotator member  49  which will be described later more in detail. 
         [0078]    The lower portion of the cam member  39  is provided on its outer peripheral surface with a plurality of guide ribs  40  at regular intervals in the circumferential direction so as to cooperate with the lock bolt guide grooves  29  of the second supporting protuberance  28 . 
         [0079]    The cam member  39  is formed with a through-hole  41  extending from its upper end to its lower end in the axial direction in which the lock bolt  34  is to-and-fro movable. 
         [0080]    This through-hole  41  has at its upper end a regular shape matching the shape of the coupling protuberance  36  and is provided at a position associated with the coupling hole  37  with a continuous hole  43  (See  FIG. 6 ) adapted to receive a coupling pin  42 . 
         [0081]    A lower portion of the through-hole  41  is conically shaped so as to receive an end of the spring  44 . 
         [0082]    The end of the spring  44  is positioned by an end surface of the lock bolt  34  disposed in the upper portion of the through-hole  41 . 
         [0083]    The cam member  39  is provided on its outer peripheral surface with a pair of helical cam grooves  45  each having a substantially semicircular cross-section opposed to each other in a radial direction. 
         [0084]    These cam grooves  45  function to convert a rotating force of the rotator member  49  to a linear movement of the lock bolt  34  by intermediary of the cam member  39 . 
         [0085]    In each of these cam grooves  45 , a given region in the vicinity of one end (i.e., lower end) is previously set as the locked region of the steering shaft  2  by the lock bolt  34  and a given region in the vicinity of the other end (i.e., upper end) is previously set as the unlocked region of the steering shaft  2  by the lock bolt  34 . 
         [0086]    The electric motor  46  serves as a power source to drive the lock bolt  34  and mounted in the space  11  for the control board of the housing by the intermediary of the motor cover  47 . 
         [0087]    The electric motor  46  normally rotates to move the lock bolt  34  forward and reversely rotates to move back the lock bolt  34 . The output shaft thereof is provided with a worm (not shown) in the form of a spiral wheel. 
         [0088]    The transmission mechanism serves to transmit a drive force of the electric motor  46  to the lock bolt  34  via the cam member  39  so that the lock bolt  34  may be moved between the locking position and the unlocking position. Specifically, the transmission mechanism comprises the cam grooves of the cam member  39 , the rotator member  49  containing this cam member  39  therein in to-and-fro movable manner, and a cam follower  56  interposed between the rotator member  49  and the cam member  39 . 
         [0089]    The rotator member  49  is provided in the form a cylinder having its inner diameter slightly larger than the cam member  39  and interposed between the housing  10  and the housing cover  25  so as to be rotatably supported without being moved in the axial direction. 
         [0090]    More specifically, the rotator member  49  has one end  50  (i.e., upper end) adapted to fit to the inner periphery of the first supporting protuberance  19  and the other end  51  (i.e., lower end) adapted to fit to the outer periphery of the second supporting protuberance  28 . 
         [0091]    The rotator member  49  is further provided around its upper portion with a worm wheel  52  formed around its periphery with a plurality of spiral teeth extending around the outer periphery from the lower portion of the first supporting protuberance  19  containing therein the upper end  50  engaged with the inner periphery thereof. 
         [0092]    The worm wheel  52  is engaged with teeth of a worm (not shown) of the electric motor  46  extending in a tangential direction when the electric motor  46  has been mounted to the housing  10  and thereby rotates the rotator member  49  around its axis. 
         [0093]    Between the worm wheel  52  and the upper end  50  of the rotator member  49 , a groove  53  for securely insertion of the first supporting protuberance  19  is defined. 
         [0094]    The worm wheel  52  is formed on its lower portion with a switch cam (not shown) operatively associated with the rotator member  49  to detect a position to which the lock bolt has moved forward. 
         [0095]    The rotator member  49  is provided on its inner peripheral surface with a diametrically opposed pair of longitudinal grooves  55  each having a semicircular cross-section extending upward in the axial direction from an inner side lower end defined above the lower end  51 . 
         [0096]    The cam follower  56  is provided in the form a spherical steel ball and disposed in the longitudinal groove  55  of the rotator member  49  as shown by  FIGS. 1 and 6 . 
         [0097]    In a state that a portion of the steel ball  56  exposed from this longitudinal groove  55  is put in the cam groove  45  of the cam member  39 , rotation of the rotator  49  causes the longitudinal groove  55  to be rotated in the circumferential direction and thereby causes the steel ball  56  as the cam follower to slide along the cam groove  45  of the cam member  39  restricted to rotate. In this way, the cam follower  56  in the form of the steel ball drives the lock bolt  34  by the intermediary of the cam member  39  to move to-and-fro along the rotational axis of the rotator member  49 . 
         [0098]    The control board  70  functions to control operation of the electric motor  46  and comprises a microswitch (not shown) cooperating with the rotator member  49  to detect a position to which the lock bolt  34  moved forward and the connector  72  connected to a main microcomputer (ECU) loaded on the vehicle. 
         [0099]    In the view of the fact that the lock bolt  34  moves forward or rearward depending on rotation of the rotator member  49 , the position to which the lock bolt  34  has moved forward is determined on the basis of ON or Off of the microswitch turned by the switch cam of the rotator member  49  (not illustrated). 
         [0100]    The connector  72  is preferably mounted not to project from the housing  10  as well as from the housing cover  25 . 
         [0101]    In this way, it is possible to prevent the electric components mounted on the control board  70  from destroyed even if a shock is exerted on the connector  72 . 
         [0102]    The outer end surface  72   a  of the connector  72  is surrounded by the edge  15   a  of the notch  15  of the housing  10  and the edge  27   a  of the wall  27  of the housing cover  25 . 
         [0103]    In other words, in the housing  10  as well as in the housing cover  25 , the position for the connector  72  is in appropriately recessed condition. 
         [0104]    Such unique construction advantageously facilitates a pair of the associated connectors to be gropingly connected to each other within a tight space containing therein the lock device  1  and thereby allows a workability to be improved. This is for the reason that the edge  15   a  of the notch  15  formed in the housing  10  cooperates with the edge  27   a  of the wall  27  of the housing cover  25  to function as guide means to find the pair of associated connectors by touch. 
         [0105]    As will be apparent from  FIGS. 3 and 4 , this particular embodiment is characterized in that the cover member  100  integrally comprises the buffering member  120  adapted to cover the front side  16   a  and the bottom side  16   c  of the housing  10  and this cover member  100  is integrally mounted on the lock device  1  by the intermediary of the bracket  110 . 
         [0106]    This cover member  100  is molded from suitable resin material and comprises a rectangular bottom portion  102  and a U-shaped outer peripheral wall consisting of a pair of side walls  101   a  and a curved wall  101   b.    
         [0107]    The substantially L-shaped buffering member  120  made of resin foam and having a sufficient thickness to maintain a predetermined elasticity is bonded to the cover member  100  so as to cover the bottom portion  102  and the curved wall  101   b  of the cover member  100  from within. 
         [0108]    The wall  101   a  of the cover member  100  is provided on its upper region (i.e., upper end as viewed in  FIG. 4 ) with a pair of bosses  103 ,  103  to be aligned with the respective boss-insertion holes  111   a,    111   a  of the bracket  110  integrally mounted on the housing  10  of the lock device  1  and a threaded hole  104  to be aligned with the screw-insertion hole  112 b of the bracket  110 . 
         [0109]    It will be appreciated by those skilled in the art that the side wall  101   a  and the curved wall  101   b  of the cover member  100  are constructed in lattice-shaped fashion in order to reduce rigidity thereof so that the cover member  100  also may have a sufficient elasticity. 
         [0110]    As shown by  FIG. 5 , the steering shaft  2  to which the steering handle (not shown) is provided with an outer column tube  4 . 
         [0111]    This outer column tube  4  is a member substantially in the form of a rectangular column containing in its inner space the steering shaft  2  axially extends. 
         [0112]    A specific construction of the outer column tube  4  will not be described here in detail since it is not directly related to the feature of this embodiment. Briefly, this outer column tube  4  serves to install the lock device  1  and the other devices such as a tilt steering device  130  which will be described later around the steering shaft  2  and additionally serves for position-adjustably connection of the steering shaft  2  to a steering column pipe  140  by the intermediary of a tilt steering device  130  as will be described later and a telescopic steering device (not shown). 
         [0113]    More specifically, as will be seen in  FIGS. 6 and 9 , the outer column tube  4  is provided on its bottom side (i.e, lower side as viewed in  FIG. 6 ) with a slide engagement hole  4   a  having a trapezoidal shape defined by the same oblique angle as the slide groove  17   a  of the protuberance  17  so that the collar  17   b  of the protuberance  17  of the lock device  1  can be engaged therewith. 
         [0114]    Opposite side walls extending downward from the slide engagement hole  4   a  are formed with screw fixing holes  4   b  associated with the screw-insertion holes  17   d  of the lock device  1 . 
         [0115]    As will be appreciated from  FIG. 5 , the tilt steering device  130  provided within the outer column tube  4  includes a tilt lever  131  extending outward in the vicinity of the lower portion of the steering shaft  2 . When the driver sitting on the driver&#39;s seat pulls the tilt lever  131 , the steering shaft  2  is released so as to be vertically position-adjustable and when the driver lets the tilt lever  131  free from operation at a predetermined position, the tilt lever restores its initial position shown in  FIG. 5  by means of a restoring mechanism (not shown) and, in consequence, the steering shaft  2  is brought in a position-locked state. 
         [0116]    In this way, the steering handle (not shown) can be adjusted to the desired position for the driver. 
         [0117]    As will be apparent from  FIGS. 7 and 8 , the tilt lever  131  of the tilt steering device  130  operating to lock and release is rotatably supported on the side wall of the tilt steering device  130 . 
         [0118]    The tilt lever  131  is provided at one end thereof with a control knob  132  adapted to be operated by the driver. 
         [0119]    This control knob  132  laterally extends from the side wall on which the tilt lever  131  is rotatably supported. 
         [0120]    A particular mechanism to drive the tilt steering device  130  does not directly relate to the present invention and detailed description will be eliminated herein. 
         [0121]    Around the steering shaft  2 , there is provided a steering column cover  150  adapted to cover the steering shaft  2 , the outer column tube  4  and the tilt steering device  130  so that these components may be invisible externally. 
         [0122]    Specifically, this steering column cover  150  comprises a substantially inverted U-shaped upper cover  151  and a lower cover  152  welded together. 
         [0123]    The front side wall on the driver&#39;s side (i.e., right side as viewed in  FIG. 5 ), the cover  150  is formed with a shaft-insertion hole  153  through which the steering shaft  2  extends outward. 
         [0124]    The steering column cover  150  is assembled integrally with the outer column tube  4 , the bracket  110  of the lock device  1  and the steering shaft  2  by means of, for example, fixing bolts. 
         [0125]    The rear end (i.e., front side of the vehicle) of the upper cover  151  is housed within an instrument panel  160  disposed on a front side (i.e., left side as viewed in  FIG. 5 ). 
         [0126]    The rear end of the lower cover  152 , on the other hand, extends below the driver s seat so as to cover the steering shaft  2 . 
         [0127]    In this manner, the steering column cover  150  cooperates with the instrument panel  160  to decorate the front side of the driver&#39;s seat. 
         [0128]    As shown by  FIGS. 7 and 8 , the lower cover  152  of this steering column cover  150  is formed with a lever operating hole  154  through which the tilt lever  131  extends outward and, in addition, formed with a knob-insertion hole  155  through which the control knob  132  of the tilt lever  131  can be inserted when the steering column cover  150  is mounted on the steering shaft  2 . 
         [0129]    In the illustrated embodiment, this knob-insertion hole  155  is provided as a portion of a lock device installed recess  156 . 
         [0130]    The lever operating hole  154  is provided in the form of a slot longer than a stroke of the tilt lever  131  being driven. 
         [0131]    This is based on the assumption that the tilt steering device  130  and the telescopic steering device (not shown) used to position-adjust the steering shaft  2  in its axial direction are usually loaded on the vehicle. Specifically, the lever operating hole  154  may be formed in the manner as mentioned above to meet the requirement that a position-adjustable range in which the steering shaft  2  can be moved in its axial direction should cover a range in which the tilt lever  131  can be moved in its axial direction. 
         [0132]    The steering shaft  2  integrally comprises the steering column cover  150 , the outer column tube  4 , the lock device  1 , the tilt steering device  130  and the other components and therefore these components such as the steering column cover  150  are position-adjusted together with the steering shaft  2  by means of the tilt steering device  130  and the telescopic steering device. 
         [0133]    To assemble the lock device  1  as has been described above, first, the lock bolt  34  and the cam follower  56  integrally coupled to the cam member  39  are assembled to the rotator member  49  and then this assembly is disposed in the space  16  for the lock mechanism within the housing  10 . 
         [0134]    Subsequently, the electric motor  46  is installed within the housing  10  and then the motor cover  47  is screw-fixed to the housing  10 . 
         [0135]    Now the control board  70  is disposed outside the motor cover  7  and the control board  70  is clamped between the housing  10  and the cover  25  by screw-fixing the cover  25  to the housing  10 . 
         [0136]    The auxiliary lock mechanism  57  is disposed in the space for the auxiliary lock mechanism within the housing  10 . 
         [0137]    The housing cover  25  is screw-fixed to the housing  10 . 
         [0138]    In this case, the locking prong  32  is plunged into the through-hole  20  until the distal end of the locking prong  32  passes through-hole  20 . 
         [0139]    Then the distal end of the locking prong  32  of the housing cover  25  is put into engagement with the auxiliary lock member  57 . 
         [0140]    Thereafter, the bracket  110  is screw-fixed to the upper wall of the space  11  for the control board of the housing  10  by inserting the fixing bolts  180  through-holes  112   a  and the associated threaded holes  10   c.    
         [0141]    In the course of this operation, the positioning ribs  10   a,    10   b  projecting on the housing  10  are engaged with the positioning groove  115   a  and the positioning hole  115   b  of the bracket  110  to position the bracket  110  on the housing  10 . In this way, the bracket  110  can be easily mounted on the housing  10  by the fixing bolts  180 . 
         [0142]    To the lock device  1  assembled in this manner, the cover member  100  having its inner surface previously provided with the buffering member  120  integrally bonded by means of adhesive or the like is assembled. 
         [0143]    Specifically, the bosses  103  of the cover member  100  are engaged with the boss-insertion holes  111   a  of the bracket  110 . 
         [0144]    Then fixing bolts  181  are threadably engaged with the threaded holes  104  of the cover member  100  by the intermediary of the screw-insertion holes  112   b  of the bracket  110 . 
         [0145]    In this way, the buffering member  120  is integrally fixed to the housing  10  so as to lie on the front wall  16   a  and the bottom wall  16   c  of the space  16  for the lock mechanism. 
         [0146]    Now steps to be followed to assemble the lock device  1  to the steering shaft  2  will be described. 
         [0147]    It should be understood that the tilt steering device  130  has previously been incorporated in the steering shaft  2  before the lock device  1  is assembled to the steering shaft  2 . 
         [0148]    In a first step, the protuberance  17  of the lock device  1  having the cover member  100  attached thereto is inserted into the slide engagement hole  4   a  formed in the front portion of the outer column tube  4  of the steering shaft  2 . 
         [0149]    The inner edge of the slide engagement hole  4   a  is aligned with the slide groove  17   a  of this protuberance  17  and slidably pulled (toward the driver&#39;s seat). 
         [0150]    In consequence, the inner edge of the slide engagement hole  4   a  is engaged with the slide groove  17   a  and the lock device  1  is held in the slide engagement hole  4   a  by means of the collar  17   b  of the protuberance  17 . 
         [0151]    In this state, the threaded holes  17   d  formed in the convex portions  17   c  of the protuberance  17  are positioned to overlap the screw-fixing holes  4   b  of the outer column tube  4  so that the lock device  1  can be fixed to the outer column tube  4  by threadably engaging the bolts  180  with the threaded holes  17   d  by the intermediary of the fixing holes  4   b.    
         [0152]    Preferably, as the bolts  170  used to fix the lock device  1  to the outer column tube  4 , so-called threaded bolts of which the heads are broken under a given torque are used. 
         [0153]    In this way, it is impossible to remove the bolts lying at lower portion of the steering shaft  2  and, in addition, it is difficult to destroy the lock device  1  externally since the lock device  1  is firmly secured to the outer column tube  4  made of metal plate. 
         [0154]    As will be apparent from  FIG. 5 , the steering shaft  2  is usually positioned so that the steering handle (not shown) extends somewhat obliquely relative to the instrument panel  160 . 
         [0155]    As a result, the front wall  16   a  and the bottom wall  16   c  of the space  16  for the lock mechanism of the housing  10  covered with the buffering member  120  of the cover member  100  are positioned aside toward the driver&#39;s seat. 
         [0156]    Even if the driver is thrown forward and the driver s knees collide against the lock device  1  under an impact due to collision accident of the vehicle while the vehicle is running, the buffering member  120  effectively absorb such impact and protects the driver from any serious damage. 
         [0157]    According to the illustrated embodiment, the cover member  100  and the buffering member  120  may be formed so as to cover not only the bottom wall  16   b  of the space  16  for the lock mechanism but the entire bottom wall of the housing  10  to assure the safety against the secondary collision. 
         [0158]    In a final step, the connector of the vehicle may be connected to the connector  72  of the lock device  1  to complete the operation of assembling. 
         [0159]    In this step, as previously described, the connectors must be gropingly connected together in a limited space but the edge  15   a  of the notch  15  formed in the housing  10  cooperates with the edge  27   a  of the wall section  27  formed in the housing cover  25  to function as the guiding means for operation of connecting the associated connectors. In this way, operation of assembly is thereby facilitated. 
         [0160]    Now procedure to assemble the steering column cover  150  to the steering shaft  2  will be described below. 
         [0161]    First, the upper cover  151  and the lower cover  152  of the steering column cover  150  are attached from above and below to the outer column tube  4 . 
         [0162]    In this step, as shown by  FIG. 7 , the control knob  132  of the tilt lever  131  is inserted into the knob-insertion hole  155  formed in the lower cover  152  and the tilt lever  131  is inserted into the lever driving hole  154 . 
         [0163]    The lower cover  152  may be attached to the outer column tube  4  at a predetermined position by threadable engagement of the fixing bolts or the like to ensure that the cover member  100  of the lock device  1  attached to the region defined above the knob-insertion hole  155  is positioned to close the lock device installed recess  156  including the knob-insertion hole  154 . 
         [0164]    In this case, the bottom portion  102  of the cover member  100  of the lock device  1  is preferably coplanar with the bottom of the lower cover  152 . 
         [0165]    Such coplanar construction is effective to prevent, without provision of any addition means, the steering shaft  2  and the other components from being visible externally since the knob-insertion hole  155  except the lever driving hole  154  is closed with the bottom portion  102  of the cover member  100 . 
         [0166]    The cover member  120  may be constructed so that the bottom portion  102  of the cover member  100  is coplanar and integral with the bottom portion of the lower cover  152  to prevent the design quality from being deteriorated. 
         [0167]    The buffering member  120  attached to the cover member  100  requires a sufficient thickness to absorb any serious impact. 
         [0168]    In consequence, a clearance gap between the steering shaft  2  and the lower cover  152  can be efficiently filled. 
         [0169]    Now the lock/unlock operation of the lock device  1  attached to the steering shaft  2 , i.e., the manner in which the lock bolt  3   4  is engaged with the engagement recess  3  of the steering shaft  2  and disengaged from this recess  3  will be discussed. 
         [0170]    When the engine start is allowed by operation carried out by the driver, the electric motor  46  drives to rotate the rotator member  49  via the worm mounted on the electric motor  46  and the cam follower  56  moves integrally with the rotator member  49  along the cam groove  45  of the cam member  39 . 
         [0171]    The lock bolt  34  is driven in the axial direction (in this case, the direction in which the engagement convex  35  of the lock bolt  34  moves apart from the engagement recess  3  of the steering shaft  2 ) as the cam follower  56  moves along the cam groove  45 . 
         [0172]    Vibration generated due to drive of the electric motor  46  and vibration generated due to movement of the cam follower  56  along the cam groove  45  of the cam member  39  are transmitted to the housing  10  and thereby an operation sound is generated. 
         [0173]    However, the front wall la and the bottom wall  16   c  of the space for the lock mechanism are completely covered with the buffering member  120  having elasticity, so that the operation sound generated within the housing is absorbed by the buffering member  120 . In this way, an operation sound possibly leaking out from the lock device  1  due to operation of the electric motor  46  can be effectively alleviated. 
         [0174]    The buffering member  120  may be constructed to come in close contact with the housing  10  to ensure that vibration transmitted to the housing  10  is absorbed by the buffering member  120 . 
         [0175]    With such construction, the vibration transmitted to the housing  10  during operation of the electric motor  46  can be absorbed by the buffering member  120  and thereby the operation sound generated from the lock device  1  can be further alleviated. 
         [0176]    The steering lock device according to the invention is not limited to the particular embodiment as has been described above but may be implemented in various modified modes. 
         [0177]    For example, while the front side  16   a  and the bottom side  16   c  of the housing  10  lying on the side of the driver&#39;s seat are covered with the buffering member  120  according to the illustrated embodiment, it is possible to cover also the side surface of the space  11  for the control board in which the electric motor  45  is disposed with the buffering member  120 . 
         [0178]    With such construction, vibration generated during operation of the electric motor  46  can be reliably absorbed by the buffering member  120  and the actuation sound generated within and leaking out from the lock device  1  can be also further alleviated. 
         [0179]    In view of the fact that the lock device  1  lies between the driver&#39;s feet, the entire side surface of the housing  10  may be covered with the buffering member  120  to assure also the safety against the secondary lateral collision with the lock device  1 . 
         [0180]    While the cover member  100  is attached to the bracket  110  which is, in turn, mounted on the housing  10  according to the illustrated embodiment, it is possible to provide the housing  10  with the boss insertion holes  111   a  and the screw-insertion holes  112   b  so that the cover member  100  may be attached directly to the housing  10 . 
         [0181]    While the cover member  100  presents a substantially rectangular contour in the illustrated embodiment, the contour of the cover member  100  is not limited to this. 
         [0182]    For example, the side surface of the cover member  100  may be curved to describe a substantially elliptic arc. 
         [0183]    It is also possible to fix the bracket only by screws without use of the bosses  103 . 
         [0184]    While the knob-insertion holes  155  of the lower cover  152  is provided in a part of a lock device installed recess  156  in the illustrated embodiment, it is also possible to provide on the knob-insertion hole  155  and to cover the knob-insertion hole  155  with the cover member  100  from the inner side of the lower cover  152 . 
         [0185]    In this case, however, the lower cover  152  will be undesirably formed on its outer surface with a concave step. To avoid this, the region of the bottom portion  102  of the cover member  100  to be engaged with the knob-insertion hole  155  is preferably formed to be convex so that such convex region may be engaged with the knob-insertion hole  155  to close the knob-insertion hole  155 . 
         [0186]    While the buffering member  120  is made of resin foam in the illustrated embodiment, it is possible to use rubber or the like so far as this buffering member  120  is elastic.