Patent Publication Number: US-7716960-B2

Title: Lock device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority under 35 USC 119 from Japanese Patent Application No. 2006-186624, the disclosure of which is incorporated by reference herein. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a lock device which operates a mechanism to be operated such as a locking mechanism or the like which is the object of key operation by a key inserted in a key insertion hole, and which maintains the mechanism to be operated in a non-operating state. 
   2. Description of the Related Art 
   The structure disclosed in Japanese Patent Application Laid-Open (JP-A) No. 5-59849 is known as an example of a lock device provided at the door or the like of an automobile. This lock device has: a key cylinder provided rotatably within an accommodating hole of a cylindrical-tubular case; plural tumblers provided slidably within the key cylinder; a side bar which is provided slidably within the key cylinder, and approaches and moves away from the respective tumblers; and a lever member disposed so as to be able to rotate relative to the key cylinder, and connected to a lock device which is a mechanism to be operated. 
   In the above-described lock device, when a proper key, at which proper engaged portions are provided is inserted into the key cylinder, the plural tumblers engage respectively with the engaged portions provided at the key and slide to predetermined proper positions, and the side bar contacts predetermined abutting positions of all of the tumblers and moves from a locking position to an unlocking position. Interlockingly therewith, the side bar engages with the lever member and connects the key cylinder to the lever member. The key cylinder and the lever member thereby become integral and able to rotate. Due to the key being rotated, the locking mechanism which is the object of the key operation can be operated by the key. 
   On the other hand, when a substitute for the key, such as a key of a shape different than the proper key, or a screwdriver, or the like (these will be referred to collectively hereinafter as “improper keys”) is inserted in the key cylinder, at least one of the tumblers does not slide to the proper position, and the side bar is maintained at the locking position. In this way, the side bar does not engage with the lever member, and the key cylinder is not connected to the lever member by the side bar. Therefore, even if the key cylinder is rotated via the key, torque is not transmitted to the lever member, and the locking mechanism which is the object of the key operation cannot be operated. 
   Namely, in the lock device disclosed in JP-A No. 5-59849, if a proper key having proper engaged portions is inserted into the key cylinder and all of the tumblers which engage respectively with the plural engaged portions at the proper key move to the proper positions, the locking mechanism can be unlocked by the proper key being rotated. However, in a case in which an improper key, which has improper engaged portions or at which engaged portions are not provided, is inserted into the key insertion hole, even if this improper key is forcibly rotated, due to the key cylinder rotating idly with respect to the lever member, the locking mechanism is not unlocked. Further, because excessive force is not applied to the respective structural parts, breakage of the structural parts is prevented. 
   However, in a lock device such as that described above, at the time of unlocking, the key (the proper key) must be rotated against the rotation resistance of the key cylinder and the lever member, the operation resistance of the locking mechanism, and the like, and the torque which is transmitted from the key to the key cylinder is quite large. Accordingly, in order to reliably prevent deformation of the key, the strength along the twisting direction of the key must be made to be sufficiently large. For this reason, the material of a key used in a lock device such as described above is limited to a material having relatively high strength, such as iron, stainless steel, or the like. Further, the thickness of the key must be made to be sufficiently thick in accordance with the magnitude of the transmitted torque. 
   In order to reduce the strength along the twisting direction which is required of the key small, a lock device has been conceived of which carries out unlocking by, rather than rotating a key which is inserted in a key insertion hole of the lock device, pushing the key. However, among lock devices which operate a locking mechanism by a pushing movement, there have not been any which can effectively prevent breakage of the structural parts even if an improper key is inserted into the key insertion hole and excessive force is applied via this improper key. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to overcome the above-described problems, and a first aspect for achieving this object relates to a lock device having: a case member which is cylindrical shaped and at whose interior is formed a space extending in an axial direction; a sleeve member which is cylindrical shaped, and is disposed at the interior of the case member, and is supported by the case member and configured to move along the axial direction between a predetermined standby position and an operating position; a plunger member which is disposed at an interior of the sleeve member and configured to move along the axial direction, and which is supported by the case member via the sleeve member and configured to move between the standby position and the operating position, and in which a key insertion hole, which is for insertion of a key from an outer side at the standby position, is formed along the axial direction; a plurality of tumbler members disposed at the plunger member and configured to move along a direction orthogonal to the axial direction between proper positions, which correspond to engaged portions of a proper key at which proper engaged portions are provided, and improper positions, which do not correspond to the engaged portions, and engaging concave portions are formed in peripheral edge portions of the tumbler members, and when a proper key is inserted into the key insertion hole of the plunger member, the tumbler members engage with the engaged portions of the proper key and move to the proper positions, and when an improper key, at which shapes of engaged portions differ from the proper key, is inserted, at least one of the tumbler members is at an improper position; a side lock member disposed at the plunger member and configured to approach and move away from the tumbler members, and when an improper key is inserted in the key insertion hole and at least one of the tumbler members is at the improper position, the side lock member moves apart from the engaging concave portions of the tumbler members and connects the plunger member and the sleeve member along the axial direction, and when a proper key is inserted in the key insertion hole and all of the tumbler members move to the proper positions, the side lock member engages with the engaging concave portions of all of the tumbler members and cancels connection of the plunger member and the sleeve member; and an interlocking mechanism which, at a time when the connection of the plunger member and the sleeve member is cancelled by the side lock member, when the plunger member becomes integral with a proper key and moves to the operating position, transfers pushing force from the plunger member to a mechanism to be operated which is an object of key operation, and causes the mechanism to be operated to operate, and, at a time when the plunger member and the sleeve member are connected together by the side lock member, the interlocking mechanism cuts-off transfer of the pushing force from the plunger member and maintains the mechanism to be operated in a non-operating state, even if the sleeve member is integral with the plunger member and an improper key and moves to the operating position. 
   In the lock device relating to the first aspect, when an improper key is inserted in the key insertion hole, the plunger member and the sleeve member are connected along the axial direction by the side lock member. Accordingly, when the operator pushes the improper key, which is inserted in the key insertion hole, toward the operating position, this pushing force is transmitted to the plunger member and the sleeve member via the improper key, and the plunger member and the sleeve member become integral with the improper key and move from the standby position to the operating position. However, when the plunger member and the sleeve member become integral with the improper key and move from the standby position to the operating position, the transfer of the pushing force from the plunger member is cut-off by the interlocking mechanism, and the mechanism to be operated is maintained in a non-operating state. 
   On the other hand, when a proper key is inserted in the key insertion hole, the connection of the plunger member and the sleeve member is cancelled by the side lock member. Accordingly, when the operator pushes the proper key, which is inserted in the key insertion hole, toward the operating position, the pushing force is transferred to the plunger member via the improper key, and is not transmitted to the sleeve member. Therefore, the sleeve member remains at the standby position as is, and only the plunger member becomes integral with the proper key and moves from the standby position to the operating position. Accordingly, the pushing force from the plunger member is transmitted by the interlocking mechanism to the mechanism to be operated, and the mechanism to be operated operates. 
   In this way, in accordance with the lock device relating to the first aspect, if the operator inserts a key into the key insertion hole and pushes the key, the mechanism to be operated can be set in an operating state if the key is a proper key, and the mechanism to be operated can be maintained in a non-operating state if the key is an improper key. Accordingly, as compared with a rotary-type lock device in which operation (key operation) with respect to the mechanism to be operated is carried out by rotating the key after the key has been inserted in the key insertion hole, there is no need to transfer torque by the key at the time of the key operation by the operator, and only load along the axial direction is applied to the key. Therefore, the mechanical strength along the twisting direction which is required of the key can be made to be sufficiently small. 
   Further, if an improper key is inserted into the key insertion hole, even if the operator pushes the improper key which is inserted in the key insertion hole and moves it from the standby position to the operating position, the transfer of pushing force from the plunger member is cut-off by the interlocking mechanism, and the mechanism to be operated is maintained in the non-operating state. Accordingly, even if an improper key is inserted in the key insertion hole and the plunger member is pushed excessively via the improper key, excessive force is not applied to the structural parts of the device such as the plunger member, the sleeve member, the interlocking mechanism, and the like. Therefore, breakage of these structural parts can be effectively prevented. 
   A second aspect for achieving the above-described object relates to the lock device of the first aspect further including pressing force converting means for, when the plunger member becomes integral with a proper key and moves toward the operating position while the sleeve member remains as is at the standby position, converting a portion of operational force, which is transferred to the plunger member via the proper key, into urging force which urges the side lock member toward the tumbler members. 
   A third aspect for achieving the above-described object relates to the lock device of the first or second aspect wherein an outer peripheral anchor hole opens at an inner peripheral surface of the case member, and an accommodating hole is formed so as to pass-through the sleeve member in the direction orthogonal to the axial direction, the accommodating hole coinciding with the outer peripheral anchor hole when the sleeve member is at the standby position, the lock device further comprising: an anchor member slidably accommodated in the accommodating hole, and an outer peripheral side end portion of the anchor member is able to be inserted into and removed from the outer peripheral anchor hole, and an inner peripheral side end surface of the anchor member is made to abut an outer peripheral surface of the plunger member; and an urging member disposed within the outer peripheral anchor hole, and urging the anchor member toward inside of the sleeve member when the sleeve member is at the standby position, wherein, when a proper key is inserted in the key insertion hole and the plunger member starts to move from the standby position toward the operating position due to pressing force from the outer peripheral surface of the plunger member, the outer peripheral side end portion of the anchor member is inserted into the outer peripheral anchor hole against urging force from the urging member so that the anchor member restrains the sleeve member at the standby position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a cross-sectional view of a lock device relating to a first embodiment cut along a vertical plane which includes an axis thereof; 
       FIG. 1B  is a front view, seen from a rear side in an axial direction, of an operation lever of the lock device; 
       FIG. 2A  is a cross-sectional view of the lock device shown in  FIG. 1A  cut along the cutting line IIA-IIA; 
       FIG. 2B  is a cross-sectional view of the lock device cut along the cutting line IIB; 
       FIG. 2C  is a cross-sectional view of the lock device cut along the cutting line IIC-IIC; 
       FIG. 3A  is a cross-sectional view of the lock device cut along the vertical plane including the axis thereof, showing a state in which an improper key is inserted in a key insertion hole and a sleeve member and a plunger member have become integral and have moved to an operating position; 
       FIG. 3B  is a cross-sectional view of the lock device cut along the cutting line IIIB-IIIB, showing the aforementioned state of the lock device; 
       FIG. 4A  is a cross-sectional view of the lock device cut along the vertical plane including the axis thereof, showing a state in which a proper key is inserted in the key insertion hole and the plunger member has moved to the operating position; 
       FIG. 4B  is a cross-sectional view of the lock device cut along the cutting line IVB-IVB showing the aforementioned state of the lock device; 
       FIG. 5A  is a cross-sectional view of the lock device shown in  FIG. 4A  and  FIG. 4B  cut along the cutting line VA-VA; 
       FIG. 5B  is a cross-sectional view of the lock device along the cutting line VB-VB; 
       FIG. 5C  is a cross-sectional view of the lock device along the cutting line VC-VC; 
       FIG. 6  is a perspective view showing an example of a key used in the lock device shown in  FIG. 1A  and  FIG. 1B ; and 
       FIG. 7  is a perspective view showing the structure of a side lock plate in the lock device shown in  FIG. 1A  and  FIG. 1B . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   1. First Embodiment 
   A lock device relating to an embodiment of the present invention will be described hereinafter with reference to the drawings. 
   (Structure of the Lock Device) 
   In  FIG. 1A  through  FIG. 5C , reference numeral S indicates an axial center of a device, and description will be given hereinafter with the direction along this axial center S being the axial direction of the device. A lock device  10  relating to the first embodiment is provided as a portion of a locking mechanism for setting an opening/closing member, such as a door of an automobile, a trunk hood, a door of a glove compartment, or the like in a locking state or in an unlocking state. The lock device  10  is used in order for an operator to operate the locking mechanism by a key  12  from a locking state to an unlocking state. 
   As shown in  FIG. 1A ,  FIG. 1B , and  FIG. 2A  through  FIG. 2C , a rectangular-cylindrical shaped case member  14  which serves as an outer shell portion of the device is provided in the lock device  10 . The case member  14  is formed so as to be slender in the axial direction. The cross-sectional configuration of the peripheral wall portion of the case member  14  along the direction perpendicular to the axis is formed as a substantial rectangle whose longitudinal direction is the height-wise direction (the direction of arrow H). A cover portion  16  is formed at the case portion  14  so as to close the end portion at the axial direction distal end side (the left side in  FIG. 1A ). An opening portion  18 , through which the key  12  can be inserted, is formed in the central portion of the cover portion  16 . A plate-shaped lever guide  20 , which extends along the axial direction, is formed integrally with the case member  14  at the lower end side of the rear end portion thereof. 
   The case member  14  is disposed at an accommodating body such as a door, a vehicle body, or the like which accommodates the locking mechanism. The case member  14  is fixed to the accommodating body such that the opening portion  18  faces toward the outer side of the accommodating body. 
   As shown in  FIG. 1A ,  FIG. 1B , and  FIG. 2A  through  FIG. 2C , the lock device  10  has a rectangular-cylindrical shaped sleeve member  22  which is disposed at the interior of the case member  14 . The sleeve member  22  is formed so as to be slender in the axial direction. The cross-sectional configuration of the peripheral wall portion of the sleeve member  22  along the direction perpendicular to the axis is formed as a substantial rectangle whose longitudinal direction is the height-wise direction. The sleeve member  22  is inserted in the interior of the case member  14 , and is supported by the case member  14  so as to be slidable along the axial direction. 
   The sleeve member  22  can slide along the axial direction between a standby position shown in  FIG. 1  and an operating position shown in  FIG. 3A  and  FIG. 3B . In the state in which the sleeve member  22  is at the standby position, the distal end surface of the sleeve member  22  abuts the inner side of the cover portion  16 . When the sleeve member  22  slides from the standby position rearward by a predetermined operation stroke D (see  FIG. 3A ), the sleeve member  22  reaches the operating position. Further, the inner peripheral surface of the sleeve member  22  is a plunger-sliding surface  23  which a plunger member  42 , which will be described later, slidably abuts. 
   A step portion  26  is formed at the sleeve member  22  at the axial direction intermediate portion of the outer peripheral surface thereof. A sleeve main body  28  is formed at the distal end side of this step portion  26 , and a spring holding portion  30 , whose outer diameter is smaller than that of the sleeve main body  28  is formed at the rear end side. The sleeve main body  28  is inserted and fit into the case member  14  so as to be slidable. A return spring  32  which has a coiled portion bent in a substantially rectangular shape, is fit on the outer peripheral side of the spring holding portion  30 . 
   As shown in  FIG. 1A , a cover portion  34  is formed at the sleeve member  22  so as to close the end portion thereof at the rear end side. A rod guiding hole  36 , which passes-through in the axial direction and whose cross-section is rectangular, is formed in the central portion of the cover portion  34 . Further, a slide lever  38 , which extends from the lower end portion of the cover portion  34  toward the rear end side, is formed integrally with the sleeve member  22 . The bottom end surface of the slide lever  38  slidably abuts the top end surface of the lever guide  20  at the case member  14 . 
   A spring-supporting endplate  40  is disposed in the lock device  10  between the rear end portion at the inner peripheral surface of the case member  14 , and the outer peripheral surface of the spring holding portion  30 . The outer peripheral surface of the spring-supporting endplate  40  is fixed to the inner peripheral surface of the case member  14 , and the inner peripheral surface of the spring-supporting endplate  40  abuts the outer peripheral surface of the spring holding portion  30  so as to be slidable. In the lock device  10 , the return spring  32  is interposed between the step portion  26  of the sleeve member  22  and the spring-supporting endplate  40 , and is in a compressed state. In this way, the return spring  32  always urges the sleeve member  22  toward the standby position (refer to  FIG. 1A ). 
   As shown in  FIG. 1A ,  FIG. 1B , and  FIG. 2A  through  FIG. 2C , the lock device  10  has the plunger member  42  which is disposed at the interior of the sleeve member  22 . The plunger member  42  is formed in the shape of a substantially rectangular column which is slender in the axial direction. A plunger main body  44 , which is inserted in the sleeve member  22 , is provided at the axial direction distal end side of the plunger member  42 . A plunger rod  46 , which projects out from the central portion of the rear end surface of the plunger main body  44 , is formed integrally at the plunger member  42 . The plunger main body  44  is slidably inserted in the sleeve member  22 . The outer peripheral surface of the plunger main body  44  is a sliding surface  47  which slidably contacts the plunger-sliding surface  23  of the sleeve member  22 . Further, the plunger member  42  is supported by the case member  14  via the sleeve member  22  and configured to move between the standby position (see  FIG. 1A ) and the operating position (see  FIG. 3A  and  FIG. 4A ). 
   In the state in which the plunger member  42  is at the standby position, the distal end surface thereof abuts the inner side of the cover portion  16 . When the plunger member  42  moves rearward by the predetermined operation stroke D (see  FIG. 3A  and  FIG. 4A ) from the standby position, the plunger member  42  reaches the operating position. In the lock device  10 , as described previously, the sleeve member  22  is also supported by the case member  14  and configured to move between the standby position and the operating position. 
   As shown in  FIG. 1A , the plunger member  42  passes through the rod guiding hole  36 , and the rear end side of the plunger rod  46  projects-out toward the outer side of the sleeve member  22 . The bottom end surface of the portion of the plunger rod  46  which projects-out from the rod guiding hole  36  slidably abuts the top end surface of the slide lever  38 . Further, as shown in  FIG. 1A ,  FIG. 2A  and  FIG. 2C , a key insertion hole  48 , which extends along the axial direction, is formed in the central portion of the plunger main body  44 . The key insertion hole  48  extends from the distal end surface of the plunger main body  44  to the rear end side thereof. The cross-sectional shape of the key insertion hole  48  is the shape of a slit which is slender along the height-wise direction of the device. The cross-sectional shape of the key insertion hole  48  corresponds to the shape of the key  12  (see  FIG. 6 ) which corresponds to the standards of the lock device  10  relating to the present embodiment. The key  12  can be inserted into and removed from the key insertion hole  48 . 
   As shown in  FIG. 3A ,  FIG. 3B ,  FIG. 4A ,  FIG. 4B , and  FIG. 6 , the portion of the key  12  which is inserted in the key insertion hole  48  is formed in the shape of a slender plate, and is manufactured of a material such as a metal, a resin, a paper, a composite material thereof, or the like. An insertion guide portion  50 , whose thickness becomes thinner in the shape of a slope from the proximal end side toward the distal end side, is formed at the distal end portion of the key  12 . Each edge surface of the key  12  along the longitudinal direction thereof are an upper engaging edge  52  and a lower engaging edge  54 , respectively. As shown in  FIG. 4A ,  FIG. 4B , and  FIG. 5A , the key  12  is inserted by the operator into the key insertion hole  48  while set at a posture such that the upper engaging edge  52  is directed toward the upper side along the height-wise direction of the device. 
   As shown in  FIG. 6 , five engaging notches PE 1  through PE 5  which are respectively different in the position and the shape thereof are set along the longitudinal direction of the key  12  (the axial direction of the device) at the upper engaging edge  52  and the lower engaging edge  54  of the key  12 . Respectively and selectively at the engaging notches PE 1  through PE 5 , engaging portions  58  which are hollowed-out in V-shapes are formed, or planar engaging portions  60  are provided by not carrying out shape machining on the upper engaging edge  52  and the lower engaging edge  54 . 
   As shown in  FIG. 2A  and  FIG. 2C , a concave latch opening  62  is formed on the plunger-sliding surface  23  at the sleeve member  22 . The latch opening  62  is formed in the side surface portion at one end side (the right side in  FIG. 2A ) in the transverse direction (the direction of arrow W) at the plunger-sliding surface  23 . The inner peripheral side of the latch opening  62  opens to face the sliding surface  47  of the plunger member  42 , and the outer peripheral side thereof is closed-off. The cross-sectional configuration of the latch opening  62  along the height-wise direction of the device is formed in a substantially rectangular shape whose longitudinal direction is the axial direction of the device. 
   As shown in  FIG. 1A  and  FIG. 2C , plural (five in the present embodiment) tumbler accommodating chambers  120  through  128  are formed in slit-shapes in the plunger main body  44 . These tumbler accommodating chambers  120  through  128  are arranged at a substantially uniform pitch along the axial direction, and this pitch is substantially the same as the pitch of the five engaging notches PE 1  through PE 5  at the key  12 . 
   Each of the tumbler accommodating chambers  120  through  128  extends so as to be slender along the height-wise direction of the device. At the tumbler accommodating chambers  120 ,  124 ,  128 , which are disposed at the odd-numbered positions from the distal end side of the plunger main body  44 , the bottom end sides are open to the bottom end surface of the plunger main body  44 , and the top end sides thereof are closed-off. At the tumbler accommodating chambers  122 ,  126  which are disposed at the even-numbered positions, the top end sides thereof are open to the top end surface of the plunger main body  44 , and the bottom end sides thereof are closed-off. Further, a guide slot  130 , which is concave toward the outer peripheral side, is formed integrally in the side surface portion of the transverse direction other end side (the left side in  FIG. 2A ) of each of the tumbler accommodating chambers  120  through  128 . The guide slots  130  extend from the open ends to the intermediate portions along the directions of thickness of the tumbler accommodating chambers  120  through  128 . In this way, the widths at the entrance sides at the tumbler accommodating chambers  120  through  128  are wider, by the widths of the guide slots  130 , than the widths at the deeper sides thereof. 
   As shown in  FIG. 2A  and  FIG. 2C , a concave holder opening  64  is formed in the plunger main body  44  in the side end surface of the transverse direction other end side of the device (the left side in  FIG. 2A ). The holder opening  64  opens at the sliding surface  47  of the plunger main body  44 , with the transverse direction outer side of the holder opening  64  being the open end thereof. The transverse direction inner side end portion of the holder opening  64  overlaps the tumbler accommodating chambers  120  through  128  and the side end portions. Further, the cross-sectional configuration (the opening configuration) of the holder opening  64  along the height-wise direction of the device is the same as the opening configuration of the latch opening  62  of the sleeve member  22 . When the sleeve member  22  and the plunger member  42  are at the same position along the axial direction, the holder opening  64  coincides with the latch opening  62 , and the holder opening  64  and the latch opening  62  communicate with one another. 
   As shown in  FIG. 1A ,  FIG. 2A  and  FIG. 2C , a tumbler plate  66  is disposed so as to be slidable along the height-wise direction of the device, within each of the tumbler accommodating chambers  120  through  128  at the plunger main body  44 . The tumbler plate  66  is formed in a substantially rectangular shape whose longitudinal direction is the height-wise direction. The thickness of the tumbler plate  66  is slightly smaller than the widths of the tumbler accommodating chambers  120  through  128  along the axial direction. A rectangular seat-receiving piece  68 , which projects-out toward the outer side, is formed integrally with the tumbler plate  66  at the side end portion at the other end side along the transverse direction of the device. An engaging concave portion  74 , which is sunk in toward the inner side in a substantially trapezoidal shape, is formed in the side end surface at the one end side. Further, an insert opening  70 , which passes along the direction of thickness through the central portions of the obverse and reverse surfaces, is formed in the tumbler plate  66 . The insert opening  70  is formed in the shape of a slit which is slender along the height-wise direction of the device. The opening width of the insert opening  70  along the height-wise direction is slightly wider than a width B (see  FIG. 6 ) of the key  12 . 
   A coil spring  72  is disposed in the guide slot  130  of each of the tumbler accommodating chambers  120  through  128 . The coil spring  72  is nipped between the seat-receiving piece  68  of the tumbler plate  66  and the floor surface of the guide slot  130  so as to always be in a compressed state. In this way, the tumbler plates  66 , which are disposed within the respective tumbler accommodating chambers  120  through  128 , are always urged by the coil springs  72  toward the opening end sides of the tumbler accommodating chambers  120  through  128 . Specifically, the tumbler plates  66  within the tumbler accommodating chambers  120 ,  124 ,  128  are always urged downward, and the tumbler plates  66  within the tumbler accommodating chambers  122 ,  126  are always urged upward. 
   At the plunger member  42 , before the key  12  is inserted in the key insertion hole  48 , the key insertion hole  48  overlaps the top end sides of the insert openings  70  at the three tumbler plates  66  which are urged downward and overlaps the bottom end sides of the insert openings  70  of the two tumbler plates  66  which are urged upward, along the height-wise direction of the device. In the lock device  10 , when the key  12  is inserted into the key insertion hole  48  of the plunger member  42  which is at the standby position, the key  12  is inserted through the insert openings  70  of the respective tumbler plates  66 , and the top side edge portion or the bottom side edge portion of the insert opening  70  at each of the tumbler plates  66  press-contacts the upper engaging edge  52  or the lower engaging edge  54  at the key  12 , and engages with the engaging portions  58 ,  60 . Specifically, the tumbler plates  66  within the tumbler accommodating chambers  120 ,  124 ,  128  engage with the engaging portions  58  formed at the engaging notches PE 1 , PE 3  and PE 5  at the upper engaging edge  52 , and the tumbler plates  66  within the tumbler accommodating chambers  122 ,  126  engage with the engaging portions  60  formed at the engaging notches PE 2  and PE 4  at the lower engaging edge  54 . 
   Accordingly, in the lock device  10 , when the key  12  is inserted into the key insertion hole  48 , the five tumbler plates  66  respectively slide along the height-wise direction of the device (the sliding direction) to positions corresponding to the engaging portions  58 ,  60  which are their engagement partners at the key  12 . Here, a key code for unlocking is given in advance to the lock device  10 , and the configurations (depths) of the engaging portions  58 ,  60 , which are the engagement partners of the tumbler plates  66 , are respectively determined in accordance with the key code. 
   If the key  12  conforms to the standards of the lock device  10  relating to the present embodiment, the key  12  can be inserted into and removed from the key insertion hole  48 . As the key  12 , there exist a key in which the shapes of all of the engaging portions  58 ,  60  which are the engagement partners of the tumbler plates  66  correspond to the key code (hereinafter, such a key will be called a “proper key  12 R”), and a key in which the shape of at least one of the engaging portions  58 ,  60  which are the engagement partners of the tumbler plates  66  does not correspond to the key code. Note that the keys  12  whose shapes do not coincide with the proper key  12 R, and key substitutes such as a screwdriver and the like which can be inserted into the key insertion hole  48  in place of the key  12 , are collectively called “improper keys  12 I”. 
   In the lock device  10 , when the proper key  12 R is inserted into the key insertion hole  48 , as shown in  FIG. 4A , the five tumbler plates  66  move to the positions corresponding to the engaging portions  58 ,  60 . At this time, as shown in  FIG. 5A , the engaging concave portions  74  of the respective tumbler plates  66  move to positions at which the centers thereof along the height-wise direction substantially coincide with the axial center S of the device (hereinafter, these positions will be called “proper positions”), and are maintained at these proper positions. Here, if the tumbler plate  66  is at a position other than the proper position along the height-wise direction, that tumbler plate  66  is at an improper position. 
   In the lock device  10 , when the improper key  12 I is inserted into the key insertion hole  48 , as shown in  FIG. 3A , some of the tumbler plates  66  engage with the engaging portions  58 ,  60  and move to corresponding positions, whereas the remaining tumbler plates  66  are maintained at their initial positions without engaging with the engaging portions  58 ,  60 . In this way, at least one tumbler plate  66  definitely moves along the height-wise direction to an improper position which does not coincide with the axial center S, or is held at the initial position without moving from the initial position (=an improper position). 
   As shown in  FIG. 2A  and  FIG. 2C , a side lock plate  76  is disposed within the holder opening  64  at the plunger member  42 , so as to be slidable along the transverse direction of the device. The side lock plate  76  is formed in the shape of a substantially rectangular plate whose longitudinal direction is the axial direction. As shown in  FIG. 7 , a projecting portion  80  which extends in the axial direction is formed integrally with the side lock plate  76  at an abutting surface  78  which is the surface at the inner side in the transverse direction of the device. The cross-sectional configuration of the projecting portion  80  along the axial direction is substantially trapezoidal, and the projecting portion  80  can be inserted in and removed from the engaging concave portions  74  at the tumbler plates  66 . 
   As shown in  FIG. 2A  and  FIG. 7 , the projecting portion  80  is disposed at the central portion of the abutting surface  78  along the height-wise direction of the device. In the state in which the side lock plate  76  is held within the holder opening  64 , the center of the projecting portion  80  along the height-wise direction is positioned at substantially the same position as the axial center S. Guide surfaces  82 , which are inclined toward the inner side in the longitudinal direction of the side lock plate  76 , are formed at the respective longitudinal direction end portions of the projecting portion  80 . Further, a cam surface  88  is formed at the end portion at the distal end side along the axial direction, at an insertion surface  86  which is at the opposite side of the abutting surface  78  of the side lock plate  76 . As shown in  FIG. 2C , the cam surface  88  is inclined at a slope toward the axial center S from the rear end thereof toward the distal end side thereof. 
   In the lock device  10 , when the proper key  12 R is inserted in the key insertion hole  48  and all of the tumbler plates  66  move to the proper positions due to the proper key  12 R, the projecting portion  80  of the side lock plate  76  which is disposed within the holder opening  64  coincides with the engaging concave portions  74  of the tumbler plates  66 , and can advance into the engaging concave portions  74  (see  FIG. 4B  and  FIG. 5A ). Further, In the lock device  10 , when the improper key  12 I is inserted in the key insertion hole  48  and at least one of the tumbler plates  66  is held at an improper position by the improper key  12 I, the projecting portion  80  of the side lock plate  76  does not coincide with the engaging concave portion  74  of the tumbler plate  66  which is at an improper position, and the distal end portion of the projecting portion  80  abuts the side end portion of the tumbler plate  66  which is at an improper position. Therefore, the projecting portion  80  cannot advance into any of the engaging concave portions  74  (refer to  FIG. 2A  and  FIG. 3B ). 
   As shown in  FIG. 2A  and  FIG. 2C , in the lock device  10 , when the projecting portion  80  of the side lock plate  76  cannot advance into the engaging concave portions  74  of the tumbler plates  66 , a portion of the insertion surface  86  side of the side lock plate  76  projects-out toward the outer side along the transverse direction from within the holder opening  64 , and is held at a position (locking position) of being inserted within the latch opening  62  of the sleeve member  22 . In this way, the side lock plate  76  connects the plunger member  42  and the sleeve member  2 ) to one another along the axial direction, and the plunger member  42  and the sleeve member  22  always become integral and move between the standby position and the operating position. 
   On the other hand, as shown in  FIG. 4B ,  FIG. 5A  and  FIG. 5C , when the projecting portion  80  of the side lock plate  76  is set in the state of having advanced-in completely into the engaging concave portions  74  of the tumbler plates  66 , a portion of the insertion surface  86  side of the side lock plate  76  moves away from the interior of the latch opening  62 , and the insertion surface  86  moves along the transverse direction to a position (unlocking position) which is slightly more toward the inner side than the sliding surface  47  of the plunger member  42 . In this way, the side lock plate  76  cancels the connection of the plunger member  42  and the sleeve member  22 , and the plunger member  42  can move singly between the standby position and the operating position, while the sleeve member  22  remains as is at the standby position. 
   When the proper key  12 R is inserted in the key insertion hole  48  and the plunger member  42  is pushed via the proper key  12 R toward the operating position, because the sleeve member  22  is always urged toward the standby position by the return spring  32 , the plunger member  42  starts to move from the standby position toward the operating position, while the sleeve member  22  remains as is at the standby position. 
   At this time, an entrance side edge portion  90  (see  FIG. 2C ) of the latch opening  62  pushes the cam surface  88  of the side lock plate  76  along the axial direction toward the operating position. The cam surface  88  converts a portion of the pushing force from the edge portion  90  into urging force directed toward the tumbler plates  66 . In this way, even if the side lock plate  76  is at the locking position at the time when the proper key  12 R is inserted in the key insertion hole  48  and the plunger member  42  starts to move toward the operating position, the side lock plate  76  reliably moves from the locking position to the unlocking position simultaneously with the start of movement of the plunger member  42 . 
   As shown in  FIG. 1A  and  FIG. 1B , the lock device  10  has an operation lever  92  which is connected to the distal end portion of the slide lever  38  and is connected to the distal end portion of the plunger rod  46 . The operation lever  92  is formed in the shape of a slender plate, and is bent in a substantial V-shape along the longitudinal direction. A connection hole  94 , which is elliptical and is slender in the longitudinal direction of the lever, is formed in the proximal end portion (the lower end portion in  FIG. 1A  and  FIG. 1B ) of the operation lever  92 . Further, a connecting shaft  96 , which is shaped as a cylindrical column and whose axial direction is the transverse direction of the device, is provided at the distal end portion of the slide lever  38 . The connecting shaft  96  is inserted in the connection hole  94  of the operation lever  92  so as to be able to rotate relatively, and can move within the connection hole  94  along the longitudinal direction of the connection hole  94 . In this way, the proximal end portion of the operation lever  92  is swingably connected to the distal end portion of the slide lever  38  via the connecting shaft  96 . 
   A pushing shaft  98 , which is shaped as a cylindrical column and whose axial direction is the transverse direction of the device, is provided at the distal end portion of the plunger rod  46 . The pushing shaft  98  passes-through a vicinity of the center along the longitudinal direction of the operation lever  92 , and is connected to the operation lever  92  so as to be able to rotate relatively. Further, the distal end side of the operation lever  92  extends rearward along the axial direction from the distal end portion of the plunger rod  46 . A cylindrical-cylindrical shaped shaft-receiving member  118  is mounted to the distal end portion of the operation lever  92 . The top end portion of a connecting rod  100 , which is shaped as a slender, round bar, is connected via the shaft-receiving member  118  to the distal end portion of the operation lever  92  so as to be able to rotate relatively. The connecting rod  100  extends along the height-wise direction of the device, and the bottom end portion thereof is connected to the main body portion (not shown) of a locking mechanism. The operation lever  92  can swing between a predetermined locking position (see  FIG. 1A ) and unlocking position (see  FIG. 4A ) around the connecting shaft  96  of the slide lever  38 . 
   In the lock device  10 , as shown in  FIG. 1A , the positions of the connecting shaft  96  and the pushing shaft  98  along the axial direction are respectively set such that, when the sleeve member  22  and the plunger member  42  are at the standby position, the operation lever  92  is held at the locking position. 
   Further, as shown in  FIG. 4A  and  FIG. 4B , when only the plunger member  42  moves from the standby position to the operating position in the state in which the sleeve member  22  is at the standby position, the pushing shaft  98  moves rearward along the axial direction with respect to the connecting shaft  96 , and pushing force along the axial direction is applied to the operation lever  92  from the plunger member  42  via the pushing shaft  98 . In this way, the operation lever  92  swings from the locking position toward the unlocking position around the connecting shaft  96 , and, when the plunger member  42  reaches the operating position, the operation lever  92  is swung to the unlocking position. 
   When the operation lever  92  swings from the locking position toward the unlocking position, the operation lever  92  transmits pushing force (operating force) along the height-wise direction of the device to the main body portion of the locking mechanism via the connecting rod  100 , while moving the connecting rod  100  downward. The state of the main body portion of the locking mechanism, which receives this operating force, changes from a locking state to an unlocking state, and the opening/closing member, such as the door, the trunk hood, the glove compartment door, or the like which was locked by the locking mechanism, becomes able to open. 
   Further, when the opening/closing member which has been opened is to be closed again, the main body portion of the locking mechanism transfers pushing force (return force) to the operation lever  92  via the connecting rod  100 , and urges the operation lever  92 , which is at the unlocking position, toward the locking position. Due to this urging force from the main body portion of the locking mechanism, the operation lever  92  which is at the unlocking position returns to the locking position, and the plunger member  42  which is at the operating position returns to the standby position. 
   As shown in  FIG. 3 , in the lock device  10 , when the sleeve member  22  and the plunger member  42  become integral and move from the standby position to the operating position the operation lever  92  is held at the locking position because the relative positional relationship between the pushing shaft  98  and the connecting shaft  96  along the axial direction does not change. Accordingly, even if the sleeve member  22  and the plunger member  42  become integral and move from the standby position to the operating position, the main body portion of the locking mechanism is maintained in the locking state and is not set in an unlocking state. In this state, when the operator stops pushing toward the key  12  (in this case, a key whose configuration is different than the proper key  12 R), the sleeve member  22  and the plunger member  42  which are at the operating position return to the standby position due to the return force of the return spring  32 . 
   As shown in  FIG. 1 , in the lock device  10 , an inner peripheral anchor hole  102  which is concave is formed in each of the top end portion and the bottom end portion of the outer peripheral surface of the plunger main body  44 . An outer peripheral anchor hole  104  which is concave is formed in each of the top end portion and the bottom end portion of the inner peripheral surface of the case member  14 . The inner peripheral anchor holes  102  are disposed at the rear end side of the tumbler plates  66  at the plunger main body  44  along the axial direction. When the plunger member  42  is at the standby position, the outer peripheral anchor holes  104  are positioned at the same positions as the inner peripheral anchor holes  102  along the axial direction and the transverse direction of the device. 
   Accommodating holes  106 , which pass-through along the direction perpendicular to the axis, are formed in the sleeve member  22  in the lock device  10 . When the sleeve member  22  and the plunger member  42  are at the standby position, the accommodating holes  106  are positioned at the same positions as the outer peripheral anchor holes  104  and the inner peripheral anchor holes  102  along the axial direction and the transverse direction. The cross-sectional configurations of the outer peripheral anchor holes  104 , the inner peripheral anchor holes  102 , and the accommodating holes  106  along the axial direction coincide with one another. 
   As shown in  FIG. 1A  and  FIG. 2B , in the lock device  10 , anchor bars  108 , which are shaped as substantially rectangular columns, are accommodated in the accommodating holes  106  so as to be slidable along the direction perpendicular to the axis, and urging plates  110  and springs  112  are inserted in the outer peripheral anchor holes  104 . The end surfaces at the outer peripheral sides of the anchor bars  108  (rear end surfaces) are flat surfaces which are parallel to the axial direction. The distal end surfaces of the anchor bars  108  are cam surfaces  116  which are shaped as flat plates which are inclined toward the outer peripheral side from the rear ends toward the distal ends along the axial direction. 
   When the sleeve member  22  is at the standby position, in the state in which the rear end surfaces of the anchor bars  108  press-contact the plate-shaped urging plates  110 , the rear end portions of the anchor bars  108  can be inserted into and removed from the outer peripheral anchor holes  104 . When the sleeve member  22  and the plunger member  42  are at the same position along the axial direction, the distal end portions of the anchor bars  108  are inserted in the inner peripheral anchor holes  102  so as to be able to be inserted into and removed therefrom, and press-contact the floor surface portions of the inner peripheral anchor holes  102 . The urging plates  110  are slidably inserted in the outer peripheral anchor holes  104 . The springs  112  are disposed in compressed states between the urging plates  110  and the floor surface portions of the outer peripheral anchor holes  104 . 
   In the lock device  10 , when the proper key  12 R is inserted in the key insertion hole  48  and the plunger member  42  starts to move from the standby position to the operating position, due to the cam surfaces  116  of the anchor bars  108  receiving a component of force (pushing force) along the direction perpendicular to the axis from the outer peripheral surface of the plunger member  42 , the anchor bars  108  are pushed-out toward the outer peripheral side against the urging forces of the springs  112 . In this way, as shown in  FIG. 4A , the rear end portions of the anchor bars  108  are inserted in the outer peripheral anchor holes  104 . At this time, because the anchor bars  108  are at positions which straddle the borders between the outer peripheral anchor holes  104  and the accommodating holes  106 , the sleeve member  22  is restrained at the standby position. When the plunger member  42 , which had moved toward the operating position, returns to the standby position, the anchor bars  108  move toward the inner side due to the urging forces of the springs  112  and the distal end portions of the anchor bars  108  are inserted in the inner peripheral anchor holes  102 . 
   On the other hand, when an improper key  12 I whose shape is different than that of the proper key  12 R is inserted into the key insertion hole  48  and the plunger member  42  is connected to the sleeve member  22  by the side lock plate  76 , the anchor bars  108  are held within the accommodating holes  106  and the inner peripheral anchor holes  102 , and the sleeve member  22  and the plunger member  42  become integral and move along the axial direction. 
   (Operation of Lock Device) 
   Operation of the lock device  10  relating to the present embodiment will be described in the following. 
   In the lock device  10 , when the proper key  12 R is inserted into the key insertion hole  48  by the operator and the plunger member  42  is pushed toward the operating position via the proper key  12 R, only the plunger member  42  starts to move from the standby position toward the operating position, while the sleeve member  22  is restrained at the standby position by the anchor bars  108 . Interlockingly with this movement of the plunger member  42  toward the operating position, the operation lever  92 , which has been at the locking position, swings toward the unlocking position. When the plunger member  42  reaches the operating position, the operation lever  92  swings to the unlocking position, and the main body portion of the locking mechanism, which has been in the locking state, is set in the unlocking state. In this way, the opening/closing member, which has been locked by the locking mechanism, is unlocked, and becomes able to open. Thereafter, when the opened opening/closing member is closed again, due to return force being transmitted to the operation lever  92  from the main body portion of the locking mechanism via the connecting rod  100 , the operation lever  92  which has been at the unlocking position returns to the locking position, and the plunger member  42  which has been at the operating position returns to the standby position. 
   Further, in the lock device  10 , when the improper key  12 I, such as the key  12  whose shape is different than the proper key  12 R or a key substitute or the like, is inserted into the key insertion hole  48  by the operator, the sleeve member  22  and the plunger member  42  are connected by the side lock plate  76 . In this way, when the plunger member  42  is pushed toward the operating position via the improper key  12 I, the plunger member  42  and the sleeve member  22  become integral and start to move from the standby position toward the operating position. In the lock device  10 , even if the plunger member  42  and the sleeve member  22  reach the operating position after having become integral, the operation lever  92  which is at the locking position does not swing, and therefore, the main body portion of the locking mechanism is maintained in the locking state as it has been. Thereafter, when the operator stops pushing toward the improper key  12 I, due to the restoring force of the return spring  32 , the plunger member  42  and the sleeve member  22  become integral and return to the standby position. 
   Accordingly, in the lock device  10  relating to the present embodiment, when an operator inserts the key  12  into the key insertion hole  48  and pushes the key  12  along the axial direction of the device, if the key  12  is the proper key  12 R, the main body portion of the locking mechanism is set in an unlocking state, on the other hand, if the key  12  is the improper key  12 I, the main body portion of the locking mechanism can be maintained in the locking state. Therefore, comparing with a rotary-type lock device in which operation of the mechanism to be operated is carried out by rotating the key after inserting the key into the key insertion hole, there is no need for torque transmission by the key  12  at the time of key operation by the operator, and only load along the axial direction is basically applied to the key  12 . Therefore, the mechanical strength along the twisting direction, which is required of the key  12 , can be made to be sufficiently small. 
   As a result, in accordance with the lock device  10  relating to the present embodiment, it is not absolutely necessary to manufacture the key  12  from a material with high mechanical strength, such as iron, stainless steel, or the like. The key  12  can be manufactured of a material, which has a low strength and is regarded to be difficult to be used as a material for a key, such as, for example, plastic, water proof-treated paper, aluminum alloys, magnesium alloys, and the like. Further, as compared with conventional keys, even if the thickness of the key  12  is made to be much thinner, problems such as deformation and the like do not arise. 
   In the lock device  10 , even if an improper key  12 I such as a screwdriver or the like is inserted in the key insertion hole  48  and this improper key  12 I is pushed toward the operating position, the plunger member  42  and the sleeve member  22  merely become integral and move from the standby position to the operating position, and the main body portion of the locking mechanism is not set in the unlocking state, and further, excessive force is not applied to the structural parts of the device such as the case member  14 , the sleeve member  22  and the plunger member  42 , and the tumbler plates  66 , the side lock plate  76  and the like which are disposed thereat. Therefore, breakage of these structural parts can be effectively prevented. 
   Further, in the lock device  10 , when the key  12  is inserted into the key insertion hole  48 , the plural tumbler plates  66  respectively engage with the engaging portions  58 ,  60  which are provided at the upper engaging edge  52  and the lower engaging edge  54  of the key  12 , and move along the direction perpendicular to the axis to positions corresponding to the engaging portions  58 ,  60 . 
   In the case when the proper key  12 R is inserted in the key insertion hole  48  and all of the tumbler plates  66  move to the proper positions corresponding to the proper engaging portions  58 ,  60 , the side lock plate  76  engages with the engaging concave portions  74  at the tumbler plates  66 , and cancels the connected state of the sleeve member  22  and the plunger member  42 . 
   On the other hand, in the case when the improper key  12 I is inserted in the key insertion hole  48  and at least one of the tumbler plates  66  does not move to the position corresponding to the proper engaging portion  58 ,  60 , the side lock plate  76  moves apart from the engaging concave portions  74  of the tumbler plates  66 , and connects the sleeve member  22  and the plunger member  42 . 
   As a result, in the lock device  10 , the plural tumbler plates  66  are made to engage respectively with the plural engaging portions  58 ,  60  at the key  12 , and the position (the locking position or the unlocking position) of the side lock plate  76  is changed in accordance with the position (the locking position or the unlocking position) of the tumbler pins of the plural tumbler plates  66 , and, in accordance with the position of the side lock plate  76 , the sleeve member  22  and the plunger member  42  are connected or the connecting of the sleeve member  22  and the plunger member  42  is cancelled. Therefore, because the pitch of the plural tumbler plates  66  can be made to be shorter than the stroke D of the plunger member  42 , the dimensions of the plunger member  42  and the key  12  along the axial direction can be made to be short and the dimension of the device along the axial direction can be shortened efficiently, as compared with a lock device in which, for example, plural tumbler pins are made to engage respectively with plural engaged portions at a key, and, in accordance with the positions (the locking positions or the unlocking positions) of the plural tumbler pins, the sleeve member  22  and the plunger member  42  are connected by the respective tumbler pins or the connecting of the sleeve member  22  and the plunger member  42  is cancelled. 
   Moreover, in the lock device  10 , when the proper key  12 R is inserted in the key insertion hole  48  and the plunger member  42  starts to move from the standby position toward the operating position, the anchor bars  108  are inserted into the outer peripheral anchor holes  104  against the urging forces of the springs  112  by the pushing force from the outer peripheral surface of the plunger member  42 , and restrain the sleeve member  22  at the standby position. In this way, at the time when the plunger member  42  moves from the standby position to the operating position, the sleeve member  22  can be reliably held at the standby position. Accordingly, the sleeve member  22  can be prevented from moving from the standby position toward the operating position due to frictional force from the plunger member  42  or the like, and the operation lever  92  can be reliably swung from the locking position to the unlocking position. 
   Note that, in the above description relating to the present embodiment, a case is described in which the lock device  10  is applied to a locking mechanism for locking or unlocking an opening/closing member. However, the lock device  10  relating to the present embodiment can be applied to any type of mechanism to be operated, provided that it is a mechanism (a mechanism to be operated) whose operational state is changed by operation of the proper key  12 R (a mechanism that changes from one of a non-operating state and an operating state to the other). 
   Moreover, in the lock device  10 , the connecting shaft  96  of the sleeve member  22  is connected to the operation lever  92  so as to be able to rotate relatively, and the pushing shaft  98  of the plunger member  42  is connected to the operation lever  92  so as to be able to rotate relatively. However, it suffices for the pushing shaft  98  of the plunger member  42  to merely press-contact the end surface at the distal end side along the axial direction of the operation lever  92 , without the pushing shaft  98  being rotatably connected to the operation lever  92 . If the pushing shaft  98  can be made to press-contact the operation lever  92  in this way, the pushing force from the plunger member  42  can be transmitted to the operation lever  92  via the pushing shaft  98 , and the operation lever  92  can be made swing toward the unlocking position as the plunger member  42  moves toward the operating position. Further, in this case, because there is no need to allow movement of the connecting shaft  96  along the longitudinal direction of the operation lever  92 , it suffices for the connection hole  94  at the operation lever  92  to be a round hole having an inner diameter which corresponds to the outer diameter of the connecting shaft  96 .