Patent Publication Number: US-10328792-B2

Title: Lid device

Description:
This application is a continuation application of U.S. patent application Ser. No. 15/038,790 entitled LID DEVICE, filed May 24, 2016, the disclosure of which is fully incorporated herein by reference. U.S. patent application Ser. No. 15/038,790 claims priority benefit of International Application Serial No. PCT/JP2014/005951 filed on Nov. 27, 2014. International Application Serial No. PCT/JP2014/005951 claims priority benefit to Japanese Patent Application No. 2013-249240 filed Dec. 2, 2013. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a lid device having a function to releasably lock a hinged lid in a closed position and a function to push out the lid from the closed position to a ready-to-open position, and in particular to a fuel lid device that can releasably lock a fuel lid, for selectively exposing a fuel filler opening provided on a vehicle body, in a closed position. 
     BACKGROUND OF THE INVENTION 
     A fuel lid (fuel door) is hinged to a vehicle body, and when closed, conceals the fuel filler opening and conforms to the outer profile of the vehicle body. The fuel filler opening is normally closed by a fuel cap. The fuel lid may be locked in order to avoid the fuel lid from opening inadvertently. 
     For instance, in a certain type of fuel lid device, the fuel lid is automatically locked when closed, and a lever provided in the cockpit of the vehicle enables the driver to release the lock and pop open the fuel lid by pulling the lever. In addition to the types of fuel lid devices that can releasably lock the fuel lid, the lid devices that can be opened and closed by pushing the lid toward the vehicle body are also known. Such fuel lids are known to be convenient for motorists who use self-service gas stations. One such example is disclosed in Patent Document 1. The disclosed device is provided with a push lifter for opening and closing the fuel lid by alternately taking the retracted position and the extended position each time the fuel lid is pushed. Additionally, an electric motor is provided such that the motor shaft extends perpendicularly to the lengthwise direction of the push lifter. The motor shaft is coaxially provided with a screw which threads into a plunger coaxially disposed with the motor shaft so that the rotation of the electric motor causes the plunger to be moved in the axial direction away from the electric motor until the free end of the plunger is received in a lock hole of the fuel lid to lock the fuel lid. When the rotation of the motor is reversed, the plunger moves in the axial direction toward the motor until the free end of the plunger is disengaged from the lock hole of the fuel lid, and the lock of the fuel lid is released. 
     PRIOR ART DOCUMENT(S) 
     Patent Document(s) 
     
         
         Patent Document 1: DE102008057860A 
       
    
     SUMMARY OF THE INVENTION 
     Task to be Accomplished by the Invention 
     According to the lid device proposed in Patent Document 1, the motor and the plunger are disposed in a coaxial relationship. Therefore, a significant space is required, and the freedom in laying out the component parts is restricted. Also, a complex assembly work is required. 
     The present invention was made in view of such problems of the prior art, and has a primary object to provide a highly compact lid device. 
     Means to Accomplish the Task 
     To achieve such an object, a certain aspect of the present invention provides a lid device ( 20 ,  70 ) for pushing out a hinged lid ( 10 ) from a closed position to an open ready position, and for releasably locking the lid in the closed position, comprising: a push lifter ( 32 ) that alternates between an extended state for pushing the lid to the open ready position and a retracted state for permitting the lid to be placed in the closed position each time a free end of the push lifter is pushed by the lid; a drive unit ( 46 ) positioned near the push lifter; a lock member ( 18 ,  72 ) moveable between an engage position for engaging the lid in the closed position and a release position for releasing the lid; and a transmission mechanism ( 64 ,  76 ) for transmitting a drive force of the drive unit to the lock member to move the lock member between the engage position and the release position; wherein the lock member and the transmission mechanism are positioned between the push lifter and a side profile of the drive unit remote from the push lifter, and wherein the lock member is moveable in a direction substantially perpendicular to a lengthwise direction of the push lifter and a direction from the push lifter toward the drive unit. 
     According to this arrangement, the dimension of the lid device in the direction of the motion of the lock member can be reduced. Thereby, the lid device can be formed as a compact unit which can be efficiently installed. Also, the freedom in laying out the remaining component parts can be enhanced. 
     According to another aspect of the lid device ( 20 ) of the present invention, the drive unit includes an electric motor ( 46 ) having a motor shaft ( 48 ) extending in the lengthwise direction of the drive unit, and the transmission mechanism ( 64 ) includes a pinion ( 56 ) driven by the electric motor and a rack ( 58 ) fixedly attached to the lock member ( 18 ) and configured to reciprocate in a direction perpendicular to the lengthwise direction of the push lifter by meshing with the pinion. 
     The lock member can be moved between the engage position and the release position with a highly simple structure. 
     According to yet another aspect of the present invention, the transmission mechanism includes a speed reduction gear group consisting of a drive gear ( 52 ) coaxially attached to the motor shaft, a driven gear ( 54 ) disposed between the motor shaft and the push lifter and meshing with the drive gear, the driven gear having a larger number of teeth than the drive gear, and a pinion coaxially attached to the driven gear and having a smaller number of teeth than the driven gear. 
     According to this arrangement, the rotational speed of the motor can be reduced to a sufficient extent without preventing the compact design of the lid device. 
     According to yet another aspect of the present invention, the rack is provided with rack teeth ( 62 ) provided in a slot ( 6 ) as internal teeth, and the pinion projects into the slot. 
     According to this arrangement, the structure for slidably supporting the rack can be simplified, and the size of the lid device can be minimized. 
     According to yet another aspect of the present invention, the drive unit includes an electric motor ( 46 ) having a motor shaft ( 48 ) extending in the lengthwise direction of the drive unit, and the transmission mechanism ( 76 ) includes a worm ( 98 ) coaxially attached to the motor shaft, a worm wheel ( 104 ) having internal teeth ( 100 ) and external teeth ( 102 ) meshing with the pinion and a rack ( 106 ) fixedly attached to the lock member and configured to reciprocate in a direction perpendicular to the lengthwise direction of the push lifter by meshing with the internal teeth of the worm wheel. 
     Thereby, the transmission mechanism can operate in a satisfactory manner even when the viscosity of the lubricating oil should increase under a low temperature condition, and the fuel lid device can be designed as a highly compact unit. 
     According to yet another aspect of the present invention, the drive unit includes an actuator that is configured to reciprocate by a prescribed stroke, and the transmission mechanism includes a cam or a link. 
     Thereby, the number of component parts of the lid device can be reduced. 
     According to yet another aspect of the present invention, the lid device further includes a housing ( 24 ) accommodating the push lifter, the drive unit and the transmission mechanism. 
     Thereby, the lid device can be formed as an assembly that can be readily installed on the vehicle. 
     According to yet another aspect of the present invention, the housing includes a first retaining portion ( 86 ) retaining the push lifter and a second retaining portion ( 88 ) retaining the drive unit and the transmission mechanism, and separated from the first retaining portion by a partition wall ( 90 ). 
     Thereby, the second retaining portion may be placed in a water tight condition for the protection of the drive unit even when an air hole is provided in the first retaining portion for allowing an air flow created by the pushing operation of the push lifter. Furthermore, the first retaining portion and the second retaining portion may be independently designed so that a new function may added to either retaining portion without any difficulty. 
     The present invention further provides a fuel lid structure ( 2 ) comprising a fuel lid pivotally supported for opening and closing a filler opening of a vehicle body and a lid device with any of the features mentioned above and configured to lock the fuel lid in the closed position. 
     According to this arrangement, the lid device can be formed as a compact unit which can be installed on a vehicle with the fuel lid already attached thereto in an efficient manner. 
     Effect of the Invention 
     According to the present invention, the dimension of the lid device in the direction of the motion of the lock member can be reduced. Thereby, the lid device can be formed as a compact unit which can be efficiently installed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a fuel lid assembly incorporated with a fuel lid device given as a first embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of the fuel lid device of the first embodiment; 
         FIG. 3  is a perspective view of the fuel lid device of the first embodiment with a part of the housing omitted from illustration; 
         FIG. 4  is a sectional view showing an unlocked condition of the fuel lid device of the first embodiment; 
         FIG. 5  is a sectional view showing a locked condition of the fuel lid device of the first embodiment; 
         FIG. 6  is an exploded perspective view of a fuel lid device given as a second embodiment of the present invention; 
         FIG. 7 a    is a perspective view of the fuel lid device of the second embodiment in an unlocked condition with a part of the device omitted from illustration; 
         FIG. 7 b    is a perspective view of the fuel lid device of the second embodiment in a locked condition with a part of the device omitted from illustration; 
         FIG. 8 a    is a sectional view of the fuel lid device of the second embodiment in an unlocked condition; 
         FIG. 8 b    is a sectional view of the fuel lid device of the second embodiment in a locked condition; and 
         FIG. 8 c    is a sectional view of the fuel lid device of the second embodiment in a manually unlocked condition. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     The present invention is described in the following in terms of preferred embodiments with reference to the appended drawings. The directions used in the following description are based on the orientation of the device as mounted on a vehicle.  FIG. 1  is a perspective view of a fuel lid assembly  2  which is installed on a rear end part of the left side of a vehicle not shown in the drawings. However, the fuel lid assembly  2  may also be installed on the rear end, the right side or any other part of the vehicle body. 
     A filler opening housing  4  defining the general outer profile of the fuel lid assembly  2  is provided with the shape of a cup with an opening defined in the bottom end thereof, and the outboard end thereof having a comparatively large outer diameter is provided with a radial flange  6 . When the fuel lid assembly  2  is installed on the vehicle body, the fuel filler neck communicating with a fuel tank is passed into the fuel lid assembly  2 , and the open end of the fuel filter neck is closed by a cap (not shown in the drawings). A fuel lid  10  is a disk member made of metallic or plastic material, and is connected to the filler opening housing  4  via a hinge  12  so that the fuel lid  10  is enabled to open and close a fuel filler opening  8  defined on the outboard end of the filler opening housing  4 . The fuel lid  10  may also be provided with a rectangular or any other planar configuration, instead of being disk-shaped. The hinge  12  is provided on the front end side of the filler opening housing  4 , and is provided with a vertically extending hinge axis. The fuel lid  10  closes and opens the fuel filler opening  8  by pivoting about the hinge axial line. When the fuel lid  10  closes the fuel filler opening  8 , the outer surface of the fuel lid  10  continuously conforms to the outer profile of the vehicle body. The back side of the fuel lid  10  is provided with an inner lid (not shown in the drawings) which includes an engagement piece  14  projecting from a free end part of the back side of the fuel lid  10  (remote from the base end part thereof connected to the hinge  12 ). An engagement hole  16  is passed through the engagement piece  14  in the fore and aft direction in the closed state of the fuel lid  10 . A fuel lid device  20  provided with a lock member  18  ( FIG. 2 ) for engaging the engagement piece  14  by being passed into the engagement hole  16  is attached to an outer surface of the filler opening housing  4  by using screws. 
       FIG. 2  is an exploded perspective view of the fuel lid device  20 , and  FIG. 3  is a perspective view of the fuel lid device  20  with a rear case  26  of a housing  24  omitted from illustration.  FIGS. 4 and 5  are sectional views taken along a plane extending in the lateral and fore and aft direction and passing through the lock member  18 , in the unlocked state and the locked state, respectively. The fuel lid device  20  is provided with the function to open and close the fuel lid  10  and the function to releasably lock the fuel lid  10  in the closed position. 
     The fuel lid device  20  is provided with a box-shaped housing  24  made of molded plastic material for accommodating the main components of the fuel lid device  20 , and formed by combing a rear case  26  and a front case  28 . The rear case  26  is connected to the front case  28  by using screws. The housing  24  is fixedly attached to the outer surface of the filler opening housing  4 . The housing  24  or the front case  28  may be partly or entirely integrally molded with the filler opening housing  4 . If desired, the outboard side of the housing  24  may consist of an open side which is closed by a flange  6  or the like when attached to the filler opening housing  4 . 
     A push lifter  32  consisting of a rod shaped assembly and received in the housing  24  for opening the fuel lid  10  includes a push button  34 , a cam  36 , a rod  38 , an outer sleeve  40 , a spring  42  and an inner sleeve  44 . Each time the push button  34  is pressed, the push lifter  32  alternates between an extended state and a retracted state. In the retracted state, the push lifter  32  does not interfere with the fuel lid  10  in the closed position, and permits the fuel lid  10  to be maintained in the closed position. In the extended state, the push lifter  32  supports the fuel lid  10  in a slightly open state. The base end of the push lifter  32  or the inboard end of the spring  42  abuts the housing  24 , and the outer sleeve  40  is fixedly secured to the housing  24 . The push button  34  is provided with a resiliency in the lengthwise direction or in the lateral direction of the vehicle body. The inboard end of the push button  34  is fixedly attached to the outboard end of the housing  24 , and the outboard end of the push button  34  is passed through an opening provided in the flange  6  without regard to the state of the push lifter  32  (the extended state or the retracted state) so that the push button  34  may engage the fuel lid  10  at all times. The fuel lid  10  is slightly spaced from the flange  6  so that the push button  34  of the push lifter  32  may be pushed in the inboard direction even when the fuel lid  10  is in the closed position. The push lifter  32  is provided with a per se known structure, and any conventionally known push lifter may be used for the present invention. 
     The structure for releasably locking the fuel lid  10  in the closed position is described in the following. 
     An electric motor  46  serving as a drive unit for driving the lock member  18  is placed in the housing  24  such that a motor shaft  48  thereof extends in parallel with the lengthwise direction of the push lifter  32 . The lengthwise direction of the motor  46  is defined as the axial direction of the motor shaft  48 , and the length of the motor  46  is smaller than the length of the push lifter  32  in the extended state. An outboard end of the motor shaft  48  is exposed from a motor housing  50 . The motor housing  50  is fixedly secured to the housing  24  such that the bottom surface of the inboard end of the motor housing  50  is located at a substantially same height as the base end of the push lifter  32 . The cross section of the motor housing  50 , which is perpendicular to the motor shaft  48 , is provided with an elongated shape whose long side is in parallel with the vertical direction of the vehicle body. 
     The motor shaft  48  is coaxially fitted with a drive gear  52  consisting of a spur gear made of metallic or plastic material. A driven gear  54  meshing with the drive gear  52  is provided between the motor shaft  48  and the push lifter  32 . The driven gear  54  consists of a spur gear made of plastic material such as POM or metallic material, and has a larger diameter and a larger number of teeth than the drive gear  52 . A pinion  56  is fixedly attached to the outboard side of the driven gear  54  in a coaxial relationship. The pinion  56  has a smaller diameter and a smaller number of teeth than the driven gear  54 . The pinion  56  may be made of plastic material such as POM or metallic material, and may be integrally formed with the driven gear  54 . The driven gear  54  and the pinion  56  are rotatably supported by the housing  24 . The drive gear  52 , the driven gear  54  and the pinion  56  jointly form a speed reduction spur gear group. 
     The pinion  56  meshes with a rack  58  consisting of a member elongated in the fore and aft direction, and provided with a slot  60  passed through the rack  58  in the lateral direction of the vehicle body and elongated in the fore and aft direction. Rack teeth  62  meshing with the pinion  56  are formed on an inner side wall of the slot  60  extending along the length of the slot  60 . The rack  58  is made of plastic material such as POM or metallic material. The rack  58  is positioned on the outboard side of the motor  46 , and above the push lifter  32 , and is supported by the housing  24  so as to be slidable in the fore and aft direction. Because the pinion  56  is received in the slot  60 , the range of the sliding movement of the rack  58  in the fore and aft direction is limited by the abutment of the pinion  56  onto the respective axial ends of the slot  60 . 
     The lock member  18  consists of a rod member made of plastic material such as POM or metallic material, and projects forward from the front end of the rack  58 . The lock member  18  may be integrally formed with the rack  58 . The drive force of the motor  46  is transmitted to the lock member  18  via a transmission mechanism consisting of the drive gear  52 , the driven gear  54 , the pinion  56  and the rack  58  so that the lock member  18  moves forward or backward depending on the rotational direction of the motor  46 . When the rack  58  has retreated, the lock member  18  is completely received within the housing  24 . When the rack  58  has advanced, the lock member  18  projects from the housing  24 , and the front end of the lock member  18  fits into the engagement hole  16  of the fuel lid  10  after passing through an opening provided in the filler opening housing  4 . 
     The drive unit may consist of other actuators such as a solenoid that causes a reciprocating movement of a prescribed stroke, instead of the electric motor  46 , and the transmission mechanism for the drive unit may use a cam mechanism or a link mechanism. Instead of the lock member  18  consisting of a rod member configured to undergo a linear movement, other lock means such as an arcuate member having an internal teeth meshing with the pinion  56  and an arcuate member that rotates around the rotational center line of a gear rotating at a reduced speed may also be used. 
     The opening and closing action of the fuel lid  10  and the operation of the lock mechanism are described in the following. 
     When the vehicle is in operation, the fuel lid  10  is closed, and the lock member  18  is passed into the engagement hole  16  as shown in  FIG. 5 . Because the lock member  18  is retained by the housing  24  via the rack  58 , the fuel lid  10  is securely held stationary against any pivoting movement. Therefore, even when the fuel lid  10  is pulled or pushed, the fuel lid  10  is locked in the closed position owing to the engagement between the engagement hole  16  and the lock member  18 . There may be some play in the engagement between the engagement hole  16  and the lock member  18  but should be small enough not to cause the change of the push lifter  32  from the retracted state to the extended state even when the fuel lid  10  is pushed in the inboard direction. 
     The motor  46  may be linked with switches, onboard systems and an electronic control unit (ECU) of the vehicle, in particular with a door lock system, so that when the vehicle has come to a stop and the door lock is released, the motor  46  is actuated, and the motor shaft  48  is turned. The drive force of the electric motor  46  is transmitted to the rack  58  at a reduced speed via the drive gear  52 , the driven gear  54  and the pinion  56  so that the rack  58  as well as the lock member  18  fixed to the rack  58  retreats. This causes the lock member  18  to be disengaged from the engagement hole  16  of the fuel lid  10 , and the retreating movement of the lock member  18  continues until the rear end of the rack  58  abuts the rear case  26  or until the pinion  56  abuts the front end of the slot  60  of the rack  58 . At this time, the lock member  18  is fully received in the housing  24  in the released position or the unlocked position as shown in  FIG. 4 . 
     When the lock member  18  is in the released position, the lock member  18  is released from the engagement hole  16  formed in the inner lid of the fuel lid  10  so that the fuel lid  10  is freed from any restraint. The fuel lid  10  is biased by a magnetic force, a spring force or a latch mechanism so that the fuel lid  10  in the released position is held in the closed position until a force exceeding a prescribed level is applied to the fuel lid  10 . At this time, if the user pushes the fuel lid  10  in the closed position in the inboard direction, the push button  34  is forced in the inboard direction. This causes the push lifter  32  to be extended so that the fuel lid  10  is pushed out in the outboard direction. As a result, the fuel lid  10  is pushed out by the push button  34  to an open ready position in which the fuel lid  10  is slightly opened so as to project slightly from the outer profile of the vehicle body. In this open ready position, the fuel lid  10  projects only to an extent necessary for the user to be able to get a hold on the free end of the fuel lid  10 . The user is then enabled to manually open the fuel lid  10  to the fully open position which may be at an angle of more than 90 degrees from the fully closed position. The fully opened fuel lid  10  is maintained in this position by the magnetic force, the spring force or the latch mechanism until a force exceeding a prescribed level is applied thereto. When the fuel lid  10  is fully open, the user can refuel the vehicle by removing the fuel cap from the filler opening. 
     When the refueling is completed, the user puts the fuel cap back on the filler opening, and pushes the fuel lid  10  back in the inboard direction beyond the open ready position. This causes the push button  34  to be pushed in the inboard direction by the fuel lid  10 , and the push lifter  32  to be put into the retracted condition. As a result, the fuel lid  10  is brought into the fully closed position. 
     When the vehicle doors are locked thereafter, the motor  46  is actuated as a result to cause a reverse rotation of the motor shaft  48  such that the rack  58  advances forward until the front end of the rack  58  abuts the front case  28  or until the pinion  56  abuts the rear end of the slot  60  of the rack  58 . As a result, the lock member  18  projects from the housing  24 , and moves to the engage position or moves into the engagement hole  16  to lock the fuel lid  10  in the closed position. 
     In this fuel lid device  20 , because the lengthwise direction of the push lifter  32  and the lengthwise direction of the motor  46  or the axial direction of the motor shaft are parallel to each other, the fore and aft dimension and the vertical dimension of the fuel lid device  20  can be minimized. The arrangement for actuating the lock member  18  consists of a highly compact unit formed by the speed reduction spur gear group consisting of the drive gear  52 , the driven gear  54  and the pinion  56 , and the rack  58  meshing with the pinion  56 . Therefore, the arrangement for actuating the lock member  18  does not prevent the fuel lid device  20  to be designed as a highly compact unit. In the illustrated embodiment, the fuel lid device  20  is reduced in size to such an extent that the fuel lid  10  and the fuel lid device  20  may be installed on a vehicle as an integrally combined assembly or as a fuel lid assembly  2 . Thereby, the efficiency of the assembly work is improved, and the manufacturing cost can be reduced. Also, the fuel lid device  20  requires a less amount of work for installing on a vehicle, and a smaller number of component parts as compared with the wire controlled fuel lid device. 
     The second embodiment of the present invention is described in the following with reference to  FIGS. 6 to 8 . In the following description, the parts corresponding to those of the first embodiment are denoted with like numerals without necessarily repeating the description of such parts.  FIG. 6  is an exploded perspective view of the fuel lid device  70 .  FIG. 7 a    is a perspective view of the fuel lid device  70  in an unlocked condition with a front part (a viewer side part) of the device omitted from illustration, and  FIG. 7 b    is a perspective view of the fuel lid device  70  in a locked condition with a front part (a viewer side part) of the device omitted from illustration.  FIG. 8 a    is a sectional view of the fuel lid device  70  taken along a plane in parallel with the fore and aft direction and the lateral direction of the vehicle body and passing through the axial line of the lock member  72  when the lock member  72  is in an unlocked condition,  FIG. 8 b    is a similar sectional view of the fuel lid device  70  when the lock member  72  is in a locked condition, and  FIG. 8 c    is a similar sectional view of the fuel lid device  70  when the lock member  72  is in a manually unlocked condition. 
     Similarly as the first embodiment, the fuel lid device  70  is fixedly attached to the outer surface of the filler opening housing  4  so that the lock member  72  may fit into the engagement hole  16  of the fuel lid  10  to engage the engagement piece  14 . See  FIG. 1 . The fuel lid device  70  includes a housing  74 , a push lifter  32 , an electric motor  46  serving as a drive unit, a transmission mechanism  76  for transmitting the drive force of the electric motor  46  to the lock member  72 , and a release lever  78  for manually moving the lock member  72  from the engage position to the release position. 
     The housing  74  accommodating a most part of the major components of the fuel lid device  70  is made of a molded plastic member including a box shaped main body  80  having an open front end and a lid  82  covering the open front end of the main body  80 . The main body  80  and the lid  82  are provided with mutually cooperating engagement features  84  so that the main body  80  and the lid  82  may be attached to each other by engaging the corresponding engagement features  84 . The housing  74  is provided with a first retaining portion  86  for retaining the push lifter  32  and a second retaining portion  88  for retaining the motor  46  and the transmission mechanism  76 . The first retaining portion  86  and the second retaining portion  88  are separated from each other by a partition wall  90  formed in the main body  80 . The push lifter  32  is retained by the first retaining portion  86  such that the push button  34  projects from an opening provided on the outboard side of the housing  74 . The first retaining portion  86  may be provided with an air hole communicating with the exterior for permitting the flow of air caused by the pushing operation of the push button  34 . A dust seal may be provided between the opening provided on the outboard side of the housing  74  and the push button  34 . The second retaining portion  88  for retaining the motor  46  may be provided with a moisture seal interposed between the main body  80  and the lid  82 . Because the first retaining portion  86  and the second retaining portion  88  are separated from each other by the partition wall  90 , the first retaining portion  86  may be provided with the air hole while the second retaining portion  88  is sealed in a water tight manner at the same time. Furthermore, because the first retaining portion  86  and the second retaining portion  88  are separated from each other by the partition wall  90 , the two portions may be designed independently from each other so that new features may be added to the device without difficulty. For instance, the push lifter  32  is provided with a spring  42 , and the structure for preventing the push lifter  32  from popping out of the housing  74  may be provided in the first retaining portion  86  without affecting the second retaining portion  88  in any way. The upper side of the main body  80  is provided with a connector portion  92  to establishing an electric connection with a power source (not shown in the drawings). The lid  82  is provided with a through hole  94  for receiving the lock member  72  therein in a slidable manner. The fuel lid device  70  is mounted on the filler opening housing  4  with the side of the lid  82  facing the filler opening housing  4  so that the through hole  94  and the engagement hole  16  of the fuel lid  10  may align with each other. 
     The structures and the functions of the push lifter  32  and the motor  46  are similar to those of the first embodiment, and the push lifter  32  and the motor  46  are arranged in the housing  74  such that the motor shaft  48  is in parallel with the lateral direction of the vehicle body or the lengthwise direction of the push lifter  32 . The motor  46  is electrically connected to the connector portion  92  via a connecting piece  96  inserted into the connector portion  92 , and to the power source via the connector portion  92 . 
     The transmission mechanism  76  transmits the drive force of the motor  46  to the lock member  72  such that the rotation of the motor shaft  48  is converted into the linear reciprocating motion of the lock member  72 . The transmission mechanism  76  includes a worm  98  coaxially attached to the motor shaft  48  of the motor, a worm wheel  104  provided with internal teeth (internal screw thread)  100  and external teeth  102  meshing with the worm  98 , and a rack  106  fixedly attached to the lock member  72  and configured to reciprocate in the fore and aft direction by meshing with the internal teeth  100  of the worm wheel  104 . 
     The worm  98  is made of metallic or plastic material, and meshes with the external teeth  102  of the worm wheel  104 . The worm wheel  104  made of metallic or plastic material is formed with a through hole  108  extending in the direction of the rotational axis thereof and the internal teeth  100  on the inner periphery thereof. The worm  98  transmits the rotation of the motor shaft  48  to the worm wheel  104  at a reduced speed, and converts the rotation around the axis extending in the lateral direction into the rotation around the axis extending in the fore and aft direction. 
     The rack  106  is made of metallic or plastic material, and is provided with rack teeth (external screw thread)  110  meshing with the internal teeth  100  of the worm wheel  104 . The rack  106  is essentially made of a rod member having a generally rectangular cross section, and the rack teeth  110  is formed on the two sides thereof facing the inboard and outboard directions, respectively. The rack  106  is further provided with a groove  112  extending the fore and aft direction on the upper surface thereof and a through hole  114  passed from the lower surface thereof so as to communicate with the groove  112 . The lock member  72  extends forward from the front end of the rack  106 . The lock member  72  may be integrally formed with the rack  106 . The rotational motion of the worm wheel  104  is thus converted into the linear motion of the rack  106  and the lock member  72 . 
     The worm  98  has a larger diameter than the pinion  56  of the first embodiment, and actuates the worm wheel  104  with a greater torque value. Therefore, even when the viscosity of the lubricating oil should increase owing to a low temperature, the transmission mechanism  76  is able to operate properly. Therefore, the fuel lid device  70  of the second embodiment is suitable for use in cold regions. Also, because the rack  106  is positioned within the worm wheel  104 , the fuel lid device  70  can be installed in a limited space. The housing  74  is provided with a bulge  116  projecting in the upward direction in an outboard end part of the housing  74  to accommodate the worm wheel  104 , but because the connector portion  92  projects upward in a more inboard part of the housing  74 , the housing  74  can be received in a rectangular space without creating any significant dead space. Thus, the fuel lid device  70  is reduced in size to such an extent that the fuel lid device  70  may be installed on a vehicle after being attached to the filler opening housing  4  as an integrally combined assembly. Thereby, the efficiency of the assembly work is improved. 
     The lock member  72  and the rack  106  which may be integrally molded are retained by a first support member  118  and a second support member  120  mounted on the housing  74  so as to be slidable in the fore and aft direction. The worm wheel  104  is supported by being threaded onto the rack  196 . 
     The first support member  118  includes a disk-shaped base portion  122  attached to the back side of the lid  82  of the housing  74  and a pair of leg portions  124  extending rearward from the base portion  122 . The base portion  122  is centrally formed with a through hole  126  aligning with the through hole  94  of the lid  82  for slidably receiving the lock member  72 . A pair of notches  128  are formed on the periphery of the disk-shaped base portion  122  for preventing the rotation of the first support member  118  around the axial line directed in the fore and aft direction by engaging corresponding features provided on the back side of the lid  82 . Each leg portion  124  consists of a rectangular plate member. The leg portions  124  vertically oppose each other from either side of the through hole  126 , and engage the upper and lower surfaces of the rack  106  at the free end parts thereof, respectively. Thus, the rack  106  is interposed between the free end parts of the leg portions  124  such that the rack  106  is prevented from rotating when the worm wheel  104  rotates. An O ring  130  is interposed between the base portion  122  and the lid  82  to slidably receive the lock member  72  while ensuring the water tightness of the second retaining portion  88 . 
     The second support member  120  includes a columnar portion  132  extending in the fore and aft direction and a plate-shaped stopper  134  extending upward from the free end of the columnar portion  132 . The columnar portion  132  is fitted into a through hole (not shown in the drawings) formed in the rear wall (bottom wall) of the main body  80  of the housing  74 , and is normally held stationary even when the motor  46  is actuated. This through hole is disposed coaxial to the through hole  94  of the lid  82 . The rear end side of the columnar portion  132  is fitted into an O ring  136  provided on the exterior of the housing  74  to ensure the water tightness of the second retaining portion  88 . The O ring  136  is fixedly attached to the housing  74  by being interposed between the housing  74  and a cover  138  which is made of rectangular strip of sheet metal and is fixedly attached to the housing  74 . The rear end part of the columnar portion  132  extending rearward beyond the cover  138  is provided with a circumferential groove  142 . The columnar portion  132  is supported by the rack  106  by being passed through the through hole  114  of the rack  106 , and being slidably engaged by the groove  112  of the rack  106  at the free end thereof. A stopper  134  restricts the forward movement of the rack  106  and the lock member  72  relative to the columnar portion  132  by engaging the front surface of a part of a rear wall  144  of the rack  106  defining the through hole  114  when the lock member  72  is in the engage position (See  FIG. 8 b   ). When the lock member  72  is in the release position, the rearward movement of the rack  106  and the lock member  72  is restricted by the engagement of the stopper  134  by the front end surface of the groove  112  of the rack  106 , or by the engagement between the bottom wall (rear wall) of the main body  80  of the housing  74  and the rear surface of the rear wall of the rack  106  (See  FIG. 8 a   ). Therefore, the lock member  72  is enabled to move between the engage position and the release position by being actuated by the motor  46 . 
     The release lever  78  may be used for manually moving the lock member  72  from the engage position to the release position in an emergency situation such as when the lock member  72  cannot be moved from the engage position to the release position owing to a failure of the motor  46  or a wire disconnection. The rack  106 , the worm wheel  104  and the worm  98  are configured to be moved in reverse by applying an external force to the rack  106  by selecting the lead angle of the gear teeth to be greater than the friction angle. The release lever  78  is made of a molded plastic member, and includes a lanyard  146  extending in the fore and aft direction and an annular grip  148  formed in the rear end of the lanyard  146 . The front end of the lanyard  146  is fixedly attached to the second support member  120  by being engaged by the groove  142  of the second support member  120 . The annular grip  148  is dimensioned so as to be held by the finger of a user. 
     When the user pulls the release lever  78  rearward, the second support member  120  moves rearward. Because the stopper  134  of the second support member engages the rear wall  144  of the rack  106 , the rack  106  is caused to move rearward while the worm wheel  104  and the worm  98  are caused to rotate. As a result, the lock member  72  eventually moves from the engage position where the lock member  72  is passed into the engagement hole  16  of the fuel lid to the release position where the fuel lid  10  unlocked. 
     The present invention has been described in terms of specific embodiments, but is not limited by such embodiments, and can be modified and substituted in various ways without departing from the spirit of the present invention. The part of the housing  24  which slidably receives the rack  58  in the first embodiment may be formed by soft material by using a two-color injection molding process so that a sealing performance may be achieved. If the motor  46  used in the first embodiment is a high torque and low rpm type, the speed reduction gear group may be omitted. In the second embodiment the first retaining portion and the second retaining portion may consist of two separate housings that can be joined to each other. The fuel lid device of the illustrated embodiments may also be used as a lid device for locking a lid other than a fuel lid. 
     GLOSSARY OF TERMS 
     
         
           2  fuel lid assembly 
           4  filler opening housing 
           6  flange 
           8  fuel filler opening 
           10  fuel lid 
           12  hinge 
           14  engagement piece 
           16  engagement hole 
           18 ,  72  lock member 
           20 ,  70  fuel lid device 
           24 ,  74  housing 
           32  push lifter 
           46  motor 
           48  motor shaft 
           50  motor housing 
           52  drive gear 
           54  driven gear 
           56  pinion 
           58 ,  106  rack 
           60 ,  62 ,  110  rack teeth 
           64 ,  76  transmission mechanism 
           86  first retaining portion 
           88  second retaining portion 
           90  partition wall 
           98  worm 
           100  internal teeth 
           102  external teeth 
           104  worm wheel