Abstract:
A fuel filler door actuator is provided having a locking arm and an alternate action mechanism. The locking arm is selectively driveable by an electric motor to engage or disengage with the fuel filler door of an automobile. The alternate action mechanism, including a spring-biased plunger having a cam track with a cam follower riding in the track, is engageable by and mounted adjacent to the fuel filler door and is capable of linear movement with respect to the door by alternating between an inward recessed position and an outwardly extended position each time an inward force is applied to the door. In the event of a loss of electrical power to the actuator, a manual override mechanism is provided which allows unpowered opening of the fuel door.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of the filing date of U.S. Provisional patent application Ser. No. 60/145,060, filed Jul. 22, 1999, the teachings of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates in general to an actuator, and, in particular, to a fuel filler door actuator for controlling the lock state of an automobile fuel filler door. 
     BACKGROUND OF THE INVENTION 
     Conventional automobile fuel filler doors may or may not be equipped with a locking mechanism for preventing access to the fuel tank through the fuel filler assembly. Locking fuel filler doors are, however, becoming favored over the non-locking versions, especially in relatively expensive automobiles and in locations where fuel costs are relatively high. By locking the fuel filler door, an automobile owner may prevent fuel theft and vandalism by introduction of damaging contaminants to the fuel tank. 
     Known locking mechanisms for fuel filler doors include: key locks, cable release assemblies, and solenoid assemblies. Key locks are assembled directly to the fuel filler door, and are opened using a key, e.g., the ignition key. Key locks, however, create the potential for lock “freeze-up” or lock corrosion that can prevent all entry to the fuel filler. These locks also possess undesirable styling features. 
     Cable release systems generally include a mechanical door latch that is released by manipulation of a cable, e.g., inside the automobile passenger compartment. As these systems age, however, they often require excessive manual force for opening the door. In addition, extensive cable routing is required when the system is installed. 
     Solenoid systems generally have a single action, spring return motion for releasing a door which is spring biased to open. These systems require high current draw and specific dedicated wiring and switching. In addition, solenoid systems require significant space for mounting and are relatively expensive. 
     Thus, prior art fuel filler door locking mechanisms suffer from a variety of disadvantages. Generally, these mechanisms do not provide for convenient and reliable operation. In addition, these mechanisms require difficult, expensive, and cumbersome installation. 
     There is, therefore, a need in the art for a cost-effective, compact, and reliable fuel filler door lock actuator that may be conveniently operated and efficiently assembled to an automobile. 
     OBJECTS OF THE INVENTION 
     Thus, it is an object of the present invention to provide a cost-efficient, compact, and reliable fuel filler door actuator. 
     It is another object of the present invention to provide a fuel filler door actuator that may be operated through an automobile central door locking system. 
     It is another object of the present invention to provide a fuel filler door actuator which may be operated through an automobile central door locking system and which has a reliable and effective manual override mechanism. 
     It is another object of the present invention to provide a fuel filler door actuator for controlling the lock state of a fuel filler door having an exterior surface which is flush to the automobile exterior body panels, thereby improving styling by obviating the need for a finger access dimple or a pull tab on the door. 
     It is still another object of the present invention to provide a fuel filler door actuator that is inherently locking and tamper resistant. 
     Yet another object of the invention is to provide a fuel filler door actuator that may be conveniently installed by mounting to the automobile fuel filler assembly. 
     Yet a further object of the invention is to provide a fuel filler door actuator that is cost-effective to produce and install. 
     These and other objects of the present invention will become apparent from a review of the description provided below. 
     SUMMARY OF THE INVENTION 
     The present invention is organized about the concept of providing a fuel filler door lock actuator that is compact, reliable, and cost-effective. The actuator includes a locking arm and an alternate action (“push-push”) mechanism. The locking arm is selectively driveable by an electric motor to engage or disengage with the fuel filler door of an automobile. The alternate action mechanism, including a spring-biased plunger having a cam track with a cam follower riding in the track, is engageable by and mounted adjacent to the fuel filler door and is capable of linear movement with respect to the door by alternating between an inward recessed position and an outwardly extended position each time an inward force is applied to the door. In the event of a loss of electrical power to the actuator, a manual override mechanism is provided which allows unpowered opening of the fuel door. 
     In particular, an actuator consistent with the invention includes an alternate action mechanism having a plunger portion configured for mounting adjacent a fuel filler door. The plunger portion is configured to move alternately between a first inward position and an outward position upon application of a force thereto through the door. A locking arm is coupled to an electric motor through a gear train. The arm is positionable in a door lock condition by energization of the motor in a first direction when the plunger portion is in the inward position. The motor may be substantially sealed in a cavity in the housing. 
     To provide manual override, the plunger may be positionable in a second inward position that is further inward relative to the housing than the first inward position. The plunger may include a portion positioned to contact a gear in the gear train, or a feature on the gear, when the plunger is in the second inward position for rotating the gear and thereby moving the arm from the door lock condition to a door unlock condition. In one embodiment, the plunger is positioned to contact an override tooth on the gear, the override tooth being larger than a plurality of drive teeth on the gear. In another embodiment, the plunger is positioned to contact a feature on a face of the gear. 
     The actuator may further include a cam follower that rides in a cam track in the plunger. For manual override, the cam track may have an override portion, the cam follower having a portion disposed in the override portion when the plunger is in the second inward position. The cam track may include an open portion at a bottom of the plunger to facilitate assembly of the actuator. 
     The gear train may include an output gear coupled to the arm through an eccentric pin. The eccentric pin may include a portion disposed in a slot in the locking arm, and the locking arm may be pivotable about a first end connected to a housing through a pin. A second end of the arm may be positioned for engaging a portion of the fuel filler door. The coupling of the locking arm to the gear train through the eccentric pin provides “tamper resistance”, since the gear train may not be back driven by a force applied to the second end of the arm. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     For a better understanding of the present invention, together with other objects, features and advantages, reference should be made to the following detailed description which should be read in conjunction with the following figures wherein like numerals represent like parts: 
     FIG. 1 is an exploded view of an exemplary actuator according to the invention; 
     FIG. 2 is a perspective view of the actuator illustrated in FIG. 1; 
     FIG. 3 is a side view of the actuator illustrated in FIG. 1; 
     FIG. 4 is a side view of an exemplary plunger for use in conjunction with an exemplary actuator according to the invention; 
     FIG. 5 is a top view of an exemplary cam follower for use in conjunction with an exemplary actuator according to the invention; 
     FIG. 6 is an end view of the cam follower illustrated in FIG. 1; 
     FIG. 7 is a front view of an exemplary output gear for use in conjunction with an exemplary actuator in accordance with the present invention; 
     FIG. 8 is a front view of another exemplary output gear for use in conjunction with an exemplary actuator in accordance with the present invention; 
     FIG. 9 is a side view of an exemplary locking arm for use in conjunction with an exemplary actuator in accordance with the present invention; 
     FIG. 10 is a partial sectional view of a portion of an exemplary actuator consistent with the invention illustrating the locking arm in a “locked” position; and 
     FIG. 11 is a partial sectional view of a portion of an exemplary actuator consistent with the invention illustrating the locking arm in an “unlocked” position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIGS. 1-3, there is shown an exemplary fuel filler door actuator according to the invention. As shown, an exemplary actuator  10  in accordance with the present invention includes: a housing  12 ; a plunger  14 ; a compression spring  15  biasing the plunger in direction outward from the housing; a reversible fractional horsepower DC motor  16 ; a motor cover  18 ; o-rings  17  and  21 ; a pinion gear  20  driven by the motor; an output gear  22  coupled to the pinion gear; a locking arm  24 ; a cam follower  26  for riding in cam track  54  in plunger  14 ; and a housing cover  28 . In the illustrated exemplary embodiment, motor cover  18  and O-rings  17 , 21  seal the motor  16  within a cavity  11  in the housing  12 . O-ring  17  seals the cover-to-housing interface, and o-ring  21  seals the motor shaft-to-housing interface. Sealing the motor serves the function of keeping the motor sufficiently insulated from potentially combustible materials in the environment around the motor. In addition, sealing the motor prevents entry of contaminants that could cause motor malfunction. 
     The illustrated exemplary embodiment of the invention will first be described in broad general terms with a more detailed description to follow. In general, the actuator  10  locks/unlocks a vehicle fuel door  40  (FIG. 3) by allowing selective engagement and disengagement of an end  30  of locking arm  24  with a catch  32  on fuel filler door  40 . Motion of the locking arm  24  is achieved by connecting the motor  16  to the vehicle power source  34 , e.g. through the vehicle central locking system  36 . When the motor  16  is energized, the pinion gear  20  drives the output gear  22 . The eccentric pin  42  extending from the face of the output gear extends through a slot  44  in locking arm  24 , and its end  46  rests in an over-center slot  48  in the cover  28 . As the output gear  22  is rotated, the pin  42  travels in the slot  44  to cause pivoting of the locking arm  24  about a pin  50  fixed to the housing  12  and corresponding movement of the end  30  of the locking arm from a locked position  30 ′(FIG. 3) to an unlocked position  30 ″, depending on the direction of rotation of motor shaft  90 . When the actuator is in an unlocked mode, it presents the fuel door  40  to a user using an alternate action, push-to-open/push-to-close (or “push-push”) mechanism provided generally by the spring-biased plunger  14  and the travel of the end  52  of the cam follower  26  within the cam track  54 . A manual override mechanism, described below, is provided for allowing unpowered operation, e.g., in the event of a loss of electrical power. 
     With reference now to FIGS. 3-6, the alternate action mechanism of an exemplary actuator consistent with the invention will now be described in further detail. The illustrated embodiment may be useful in conjunction with flush fuel filler doors (i.e. doors having no finger access dimples or pull tabs) with an over-center spring, which biases the door alternately open or closed. Those skilled in the art will recognize, however, that an actuator according to the invention may be adapted for use with other fuel filler door arrangements, e.g., a door with a spring clip that engages a feature on the end of the plunger, or a plunger with a spring clip that engages a feature attached to the door. 
     In the case of a door with an over-center spring (not shown), the door is held in the closed position by the over-center spring. In this position, the door may rest on, or be adjacent to, an elastomer bumper  71  on the end  70  of the plunger. The plunger is held in a door closed position  14 ′ by pressing engagement of a front portion  72  of the cam track  54  against a surface of the end  52  of the cam follower  26 . In the illustrated embodiment, the cam follower is slidably disposed in a slot  27  in the housing cover. Those skilled in the art will recognize other configurations for the cam follower  26 . For example, in another embodiment, plunger  14  could move up and down with respect to a fixed cam follower, instead of the cam follower  26  moving up and down in track  54 . 
     To open the fuel filler door, the exterior surface of the door is forced inward. This depresses the plunger  14  and its outwardly biasing compression spring  15 , thereby causing the cam follower  26  to move upward in the slot  27  and the track  54  and through the portion  80  of the track  54  (FIG.  4 ). When the follower  26  reaches the upper portion  82  of the track  54 , the plunger  14  is forced outward from the housing  12  by the spring  15 . The follower  26  travels through the upper portion  82  and then down through an end portion  84  to a bottom portion  86  of the track  54 . The spring  15  thus extends the plunger  14  to push the door open in opposition to the door&#39;s over-center spring. The door is held open by the extended plunger to permit a user to insert fingers behind the door to pull it open against the force of the over-center spring. When the door is fully opened, the over-center spring biases the door in the open position. 
     To close the door, the door is pivoted in the closing direction by the operator. As the door is pivoted, the over-center spring provides a force to urge the door toward the closed position. The door stops closing when it meets the end  70  of the extended plunger  14 , which is held in the “door open” position by the plunger coil spring  15  and the positioning of the cam follower  26  in the bottom portion  86  of the track  54 . The bumper  71  on the end  70  of the plunger may absorb the impact of the door  40  on the plunger. As additional force is applied to the door, the plunger  14  is forced toward its closed position against the bias of the spring  15 , and the end of the cam follower  26  slides along the bottom portion  86  of the track to the opening  88  of the front portion  80  of the track. 
     When the door is released, the spring  15  forces the plunger  14  outward to return the door to the body flush position, and forces the end of the cam follower  26  to travel upward to rest in the portion  72  of the track  54 . Thus, the ends of travel for the plunger are defined by the cam track profile in the plunger. In the illustrated embodiment, the track is similar to what is commonly referred to as a heart cam. The bottom of the cam track  54  is open in the illustrated embodiment, which advantageously makes the actuator of this embodiment easier to assemble. In particular, the plunger may be positioned over the follower  26  after the follower is positioned in the slot  27 . 
     The alternate action mechanism would operate similarly in a door with a spring clip (not shown). If such a door were used, the door may be held in the closed position by the spring clip, which would engage a feature on the end of the plunger. When the plunger is placed into an open position, pulling on the door would overcome the spring clip to free the door for opening the rest of the way. The door would then be held open by friction or a mechanical detent. As the door is closed, the spring clip would again engage the feature on the end of the plunger. 
     With continuing reference to FIGS. 1-3, and also to FIGS. 7-8, an exemplary door locking mechanism consistent with the invention will now be described in further detail. The door locking mechanism generally includes motor  16 , pinion gear  20  which is coupled to the motor output shaft  90  for rotation therewith, output gear  22  coupled to the pinion gear  20 , locking arm  24 , and housing cover  28 . In the illustrated embodiment, the eccentric pin  42  extends through the slot  44  in the locking arm  24  with its end  46  positioned in the over-center slot  48  of the housing cover  28 . As output gear  22  rotates, eccentric pin  42  travels within slot  44  and over-center slot  48 , forcing locking arm  24  to pivot about pin  50  with the end  30  of locking arm  24  moving between the unlocked  30 ″ and locked  30 ′ positions shown in FIG.  3 . When the end  30  of locking arm  24  is in the unlocked position  30 ″, the end  46  of pin  42  is positioned in the top of over-center slot  48 , thereby resisting motion of arm  24  toward the locked position  30 ′. 
     Although in the illustrated embodiment, the end of the pin  42  is supported in the slot  48 , those skilled in the art will recognize that this configuration is not necessary. The slot  48  simply provides support for the end of the pin during operation. Where such support is deemed useful or necessary, other means of support could be provided. For example, a support surface may be formed on the interior of the housing. 
     The positioning of the pin  42 , as well as the dimensions of the slot  44 , effect the range of motion in the end of the arm, and may be adjusted depending on the requirements of the particular application. As shown in FIG. 7, however, in one embodiment, pin  42  may be positioned at a distance d of about 0.12″ from the center point P 1  of the gear  22  and about 6.1 degrees from the gear centerline that passes through the center of the override tooth  64 . An advantage of this configuration is that it is “tamper-resistant”, since the eccentric positioning of the pin  42  and the pivoting of the arm  24  about pin  50  prevent the arm from manually being moved from locked position  30 ′ to unlocked position  30 ″. 
     In particular, with reference to FIG. 10, when the arm  24  is in the “locked” position  30 ′, a force imparted to end  30  of the arm results in a force F N  which is normal to the bottom surface of the slot  44 . If the distance d 1  from the center point P 2  of the pin  46  to the center point P 1  of the gear  22  is greater than zero, a clockwise moment M CW  is generated due to the fixed pivot point P 0  of the arm about pin  50 . The clockwise moment causes the arm to maintain its locked state upon application of an external force to the end of the arm. 
     Likewise, with reference to FIG. 11, when the arm  24  is in the “unlocked” position  30 ″, a force imparted to end  30  of the arm results in a force F N2  which is normal to the top surface of the slot  44 . If the distance d 1  from the center point P 2  of the pin  46  to the center point P 1  of the gear  22  is greater than zero, a counter clockwise moment M CCW  is generated due to the fixed pivot point P 0  of the arm about pin  50 . The counter clockwise moment causes the arm to maintain its unlocked state upon application of an external force to the end of the arm. 
     Operationally, the locking sequence starts with door  40  in the closed position, but with locking arm  24  secured in the unlocked position  30 ″ by output gear  22 . Motor  16  may be energized to drive output gear  22 , thereby causing locking arm  24  to pivot from the unlocked position  30 ″ to the locked position  30 ′ with pin  42  traveling in slot  44  and from the top of over-center slot  48  to the bottom of over-center slot  48 . As discussed above, the locking arm  24  is secured into the locked position  30 ′(i.e. providing tamper resistance) due to the eccentric positioning of the pin  42  on the output gear  22 . 
     Once the door is locked, it is held from being pulled open by engagement of the end  30  of locking arm  24  with the catch  32  on the door  40 , and the door cannot be pushed far enough inward to change the state of the alternate action mechanism. To unlock the door, alternate polarity is applied to motor  16 , e.g., through the vehicle central locking mechanism  36 , and the locking arm motion is reversed. 
     Advantageously, the catch  32  and the locking arm  24  may be configured to allow the door to close even if locking arm  24  has already been moved to the locked position with the door open, i.e., the arm is in the locked position  30 ′ but the end  30  of the arm is not engaged by catch  32 . In this condition, as the door is pushed closed, an angled surface  91  on catch  32  can deflect locking arm  24  upward far enough to allow it to engage the catch  32  and establish a locked condition. A shelf  95  (FIGS. 2-3) may also be provided to prevent door  40  from being driven downwardly by the locking arm  24  during normal operation or while closing with the locking arm  24  in a “locked” position, further rendering the actuator tamper-resistant. 
     An actuator consistent with the invention may also include a manual override feature. In the illustrated exemplary embodiment, a first end of an override cable  56  may be attached to an upwardly extending tab  58  on top of the plunger  14 . A second end of the manual override cable  56  may be attached to a manual override handle  60  positioned in a convenient and/or secure location, e.g. the automobile trunk or luggage compartment. Operation of the mechanical override is accomplished by pulling on the handle  60 , thereby causing plunger  14  to retract further into the housing than it does during normal operation. In the illustrated embodiment, pulling handle  60  causes the end  52  of the cam follower  26  to be moved from its closed position in portion  72  of the track  54  into an override portion  100  of the track, allowing plunger  14  to be drawn further into the housing until a hard stop is reached. 
     As the handle  60  is pulled, cable  56  draws the plunger  14  back toward the rear of the housing  12 , causing a downwardly extending portion  62  (FIG. 4) of the plunger  14  to impact the override tooth  64  on output gear  22 . In an alternative embodiment, an output gear  22   a , as shown in FIG. 8, may be provided, and the downwardly extending portion  62  may be positioned to contact an override pin  63  extending from a face  65  of the gear. Other configurations for causing engagement of a feature on the plunger with a feature on the gear will be apparent to those skilled in the art. 
     As the portion  62  contacts the gear, the output gear  22  is rotated in a counterclockwise direction to force the end  30  of locking arm  24  out of catch  32 . This results in manual sequencing of the locking arm  24  to the unlocked position  30 ″, with the end  52  of the cam moving into the upper portion  82  of the track and then into portion  86  of the track to allow the plunger to extend outward. When the cable handle is released, the plunger spring  15  extends the plunger and moves the unlocked door to the open position. In one embodiment of the invention, a cable guide  59  may be provided to guide movement of plunger  14  via cable  56 . Also, an extra length of cable  61  may be provided for cable  56 , sufficient to prevent activation of the manual override by mere inadvertent pulling of cable  56  or handle  60 . 
     The embodiments that have been described herein, however, are but some of the several which utilize this invention and are set forth here by way of illustration but not of limitation. It is obvious that many other embodiments, which will be readily apparent to those skilled in the art, may be made without departing materially from the spirit and scope of the invention.