Abstract:
Fuel receptacles and related systems are described that are tamper resistant. A fuel receptacle can include a housing having an opening through which fuel contained therein may be delivered to a fuel consuming device along a fuel path and a biased element. The biased element can be contained with the housing having an orifice and a notch and it can sealing the opening when biased into a first position. The fuel consuming device can contain a protruding member to contact the notch and cause the biased element to move along a plane perpendicular to the fuel path into a second position when the fuel receptacle is coupled to the fuel consuming device. The second position can cause the orifice to be aligned with the opening thereby permitting fuel to be delivered to the fuel consuming device along the fuel path.

Description:
RELATED APPLICATION  
       [0001]     This application claims the benefit under U.S. Pat. App. Ser. No. 60/797,114, entitled “Tamper Resistant Fuel Cartridges,” filed May 2, 2006, the contents of which are hereby fully incorporated. 
     
    
     TECHNICAL FIELD  
       [0002]     The subject matter described herein relates to tamper resistant (also referred to as childproof) fuel receptacles such as fuel cartridges.  
       BACKGROUND  
       [0003]     Portable devices are increasingly utilizing fuel consuming devices, such as fuel cells or combustion products, in order to generate heat or electricity, or to facilitate combustion. Fuel receptacles (such as fuel cartridges) can be detachably coupled to such fuel consuming devices to provide a source of fuel. Such fuel may comprise gases, liquids, or solids which are selectively released from the receptacles. In order to ensure the integrity of the fuel contained with the fuel receptacles and to prevent unwanted access to the fuel (i.e., to childproof the receptacles), such fuel receptacles need to be tamper resistant.  
       SUMMARY  
       [0004]     In one aspect, a fuel receptacle to deliver fuel to a fuel consuming device comprises a housing and a biased element. The housing has an opening through which fuel contained therein may be delivered to the fuel consuming device along a fuel path. The biased element is contained with the housing and includes an orifice and a notch. When biased in a first position, the biased element seals the opening. The fuel consuming device contains a protruding member to contact the notch and cause the biased element to move along a plane perpendicular to the fuel path into a second position when the fuel receptacle is coupled to the fuel consuming device. When in the second position, the orifice is aligned with the opening thereby permitting fuel to be delivered to the fuel consuming device along the fuel path. The biased element can retract from the second position into the first position when the fuel consuming device is decoupled from the fuel receptacle.  
         [0005]     Numerous variations may be implemented. The housing can comprise a top portion and a bottom portion that both contain a guiding track into which the biased element slides from the first position to the second position. The biasing element can be any mechanism to cause the biased element to be biased into the first position such as a spring. The biasing element can be rectangular shaped so that it slides from the first position to a second position or it can be circular so that it rotates around a central axis from the first position to a second position. The protruding member can be wedge shaped and/or the housing can include a shield positioned between the fuel and the biased element to impede access to the fuel within the housing. The housing can contain a slot aligned with the notch when the biased element is in the first position so that the protruding member extends through to contact the notch when the fuel receptacle is coupled to the fuel consuming device.  
         [0006]     The fuel consuming device can be a fuel cell, which for example, may be incorporated into a mobile computing device (e.g., notebook computer, mobile phone, etc.). The fuel can be liquid, solid, or gas. In some variations, the fuel cell is a liquid feed direct methanol fuel cell and fuel is liquid methanol.  
         [0007]     The details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  illustrates an isometric view of a tamper resistant fuel cartridge with a portable device (i.e. notebook computer);  
         [0009]      FIG. 2  illustrates an isometric view of a tamper resistant fuel cartridge;  
         [0010]      FIG. 3  illustrates an exploded view of the tamper resistant fuel cartridge of  FIG. 2 ;  
         [0011]      FIG. 4  shows a detailed isometric view of a top housing of the variation of the tamper resistant fuel cartridge of  FIG. 2 ;  
         [0012]      FIG. 5A  depicts a trimetric view of a variation of the sliding door of the variation of the tamper resistant fuel cartridge of  FIG. 2 ;  
         [0013]      FIG. 5B  illustrates a trimetric view of the variation of the sliding door of  FIG. 5A ;  
         [0014]      FIG. 6A ,  FIG. 6B  depict a top view and a detailed trimetric view, respectively, of the variation of the tamper resistant fuel cartridge of  FIG. 2  when the variation of the sliding door of  FIG. 5  is in “open” position and a portable device (i.e., notebook computer) is in “engaged” position;  
         [0015]      FIG. 7A ,  FIG. 7B  depict a top view and a detailed trimetric view, respectively, of the variation of the tamper resistant fuel cartridge of  FIG. 2  when the variation of the sliding door of  FIG. 5  is in “closed” position and a portable device (i.e., notebook computer) is in “disengaged” position;  
         [0016]      FIG. 8  depicts an exploded view of another variation of the tamper resistant fuel cartridge of  FIG. 2 ;  
         [0017]      FIG. 9A ,  FIG. 9B  show an isometric view and a top view, respectively, of a variation of the sliding door mechanism of the variation of the tamper resistant fuel cartridge of  FIG. 2  when this mechanism is in “open” position and a portable device (i.e., notebook computer) is in “engaged” position;  
         [0018]      FIG. 10  shows a front view of a variation of the sliding door mechanism of the variation of the tamper resistant fuel cartridge of  FIG. 2  when this mechanism is in “semi-open” position  
         [0019]      FIG. 11  depicts an exploded view of another variation of the tamper resistant fuel cartridge of  FIG. 2 ;  
         [0020]      FIG. 12  shows an isometric view of a variation of the sliding door mechanism of the variation of the tamper resistant fuel cartridge of  FIG. 2  when this mechanism is in “open” position and a portable device (i.e., notebook computer) is in “engaged” position; and  
         [0021]      FIG. 13  shows an isometric view of a variation of the sliding door mechanism of the variation of the tamper resistant fuel cartridge of  FIG. 2  when this mechanism is in “closed” position and a portable device (i.e., notebook computer) is not in the “engaged” position. 
     
    
     DETAILED DESCRIPTION  
       [0022]     The subject matter described herein can be used to minimize the likelihood that materials contained within a receptacle (such as a fuel cartridge) are unintentionally released from such receptacle whether during use or transportation, or by individuals such as children. While the current description is predominantly focused on fuel cell cartridges, the techniques described herein can be applied to a wide variety of receptacles containing materials which are only selectively released such as (methanol cartridges for catalytic heaters, ink cartridges, and the like).  
         [0023]     With regard to fuel cell cartridges, the techniques described herein can be used to ensure the safety and integrity of contained fuel. Just as batteries require re-charging, fuel cells require a fuel supply to them to be replenished periodically. The primary method for fuel replenishment is replacement of a fuel cell cartridge containing the fuel. These cartridges contain volatile and often dangerous substances under pressure and their accidental release or compromise of the container can pose a danger to the user. Child resistance is of particular concern, since children are curious and may pick them up, play with them and make attempts to see what&#39;s inside.  
         [0024]     Several related techniques for ensuring safe fuel cartridge handling and, more specifically, to prevent accidental, unsafe tampering or unsafe entry by children are provided herein. Each of the following systems describes how the tamper resistant design would be integrated into a fuel cell cartridge for illustrative purposes only.  
         [0025]      FIG. 1  shows a schematic view of a portable computing device  10  (i.e., notebook computer) which may optionally include a docking station DS for a tamper resistant fuel cartridge  20 . The location of such docking station DS for the fuel cartridge  20  as illustrated is not restrictive and it may be located in any place of the portable computing device  10  that may be suitable with the dimensions of the fuel cartridge  20  herein displayed.  
         [0026]      FIG. 2  shows an isometric view of a variation of the tamper resistant fuel cartridge  20 . The tamper resistant mechanism may be implemented inside the housing of the fuel cartridge  20 . Such an arrangement may prevent a child equipped with simple household tools from obtaining access to the inside of the cartridge  20  and the fuel inside (i.e., methanol). In addition, this arrangement may be cost effective, easy to manufacture, robust, easily scaled, and difficult to bypass with or without tools. This variation of tamper resistant fuel cartridge  20  may be spring loaded (or otherwise biased) with minimal interaction from the user. When the cartridge  20  is inserted into the docking station DS, the biased component (i.e., sliding door) may open by interacting with a specially designed feature on the computing device side (i.e., a wedge design). This particular feature may press against a notch in the biased component, sliding the biased component out of the way so that fuel (i.e., methanol) may flow through the unobstructed fuel path  21  and fuel can be delivered from the fuel cartridge  20  to the computing device  10  (i.e., through a connecting fuel valve, and corresponding computing device valve). When the cartridge is removed, the biasing element retracts and closes the biased element. The outer housing of this variation of the tamper resistant fuel cartridge  20  may be structured to encase the biased element and hold it in place.  
         [0027]      FIG. 3  illustrates an exploded view of the tamper resistant fuel cartridge  20 . In this variation, the list of components that form this tamper resistant feature or mechanism may comprise: an outer top case or top housing  22 , an outer bottom case or bottom housing  23 , a biased element  24 , and a biasing element  25 . The biased element  24  may be represented by a sliding door and the biasing element may be represented by a coil or wire extension spring with end hooks (preferably double full loop end hook). All the components, as depicted in  FIG. 2 , except for this variation of spring  25 , may be manufactured with, but not limited to, polycarbonate, a blend of polycarbonate with ABS, polycarbonate with a certain percentage of glass fiber (no more than 20%), polypropylene, or LDPE (low density polyethylene). This variation of spring  25  may be manufactured of stainless steel (SS  302  or SS  316 ). It may be observed in this exploded view how a modified top housing  22  and bottom housing  23  may house this variation of tamper resistant feature by only adding two components: a biased element or sliding door  24 , and a biasing element or spring  25 . The former may be a custom designed part and the latter may be an “off-the-shelf” purchased part. Such an arrangement provides a cost effective and robust design that can be mass produced and which provides a safe user friendly environment.  
         [0028]     In this variation of the tamper resistant feature, both top housing  22  and bottom housing  23  may be designed to not only they hold the sliding door  24  in place, but also to allow the door  24  to open and close when it is required. In this variation, the features added to the top and bottom housings may be identical, due to the symmetry of this variation of a tamper resistant fuel cartridge  20 . There may be a difference for the bottom housing  23  due to the fact that this component holds the variation of the spring  25  and an added feature may be added, as shown in  FIG. 4 . The area of modification MD of bottom housing  23 , as shown in  FIG. 4 , is added to the front face FF of a standard ST configuration of a fuel cartridge. The features in area MD, added to a variation of a fuel cartridge ST, and with the biased and biasing elements, may form a tamper resistant fuel cartridge  20 . These features in area MD of the bottom housing  23  comprise, but not limited to: a door housing DH, a wedge slot WS, a wedge shield WSH, a spring post SP, and a spring holder SH.  
         [0029]     The door housing DH, as shown in  FIG. 4 , may contain a track T that holds the door in place with minimal movement (e.g., wobbling) to allow the door to be properly opened and closed. The track may guide the door as it is moved by the actions of the wedge of the computing device side and the spring  25 . This variation of the track may have a draft angle of 1° to 2°, with a negative slope or increasing draft angle as the door  24  travels farther from the spring holder feature SH. The guiding surfaces of this variation of the track T may be bottom wall and side walls. These walls may require a good surface finish so the friction created by the sliding door  24  when it moves is significantly reduced and does not impede the door movement. The width of the door housing DH may be between 3 mm and 12 mm, and it may depend on the coil diameter of the spring  25 , which may determine the volume occupied by the door housing DH.  
         [0030]     The spring holder SH, as shown in  FIG. 4 , may be a feature confined by the door housing DH. Its function may be to hold the biasing element or spring  25 , so the spring  25  may be kept at a certain height from the bottom of the door housing DH. The curvature C of the spring holder SH may be slightly bigger than the outer diameter of the spring  25 , which value may be within 3 mm to 12 mm, and always an equal or less value than the inner width of the door housing DH. The length of the spring holder SH may be within the range of 10 mm to 25 mm, and it may have a negative slope or increasing draft angle as it approaches to the center of the cartridge, where the fuel path is established. The variation of the spring  25  may be secured by the spring post SP on the spring holder SH of the door housing DH, as shown in  FIG. 4 , on the farthest side from the center of the fuel path. The dimensions of the spring post SP are such that they may provide strength and a design safety factor so the performance and safety are not compromise. These dimensions may be: height, between 5 to 10 mm; diameter, between 2 to 5 mm, so the full loop end hook of the spring  25  can be properly inserted with an appropriate radial clearance. This variations of spring holder SH and spring post SP may be designed for a variation of spring  25  to operate the variation of housing door  24 . These two features (spring holder SH and spring post SP) along with the top housing  22  once the fuel cartridge  20  is fully assembled, will prevent the spring from slipping off of this spring post SP. This spring configuration may allow the sliding door  24  to close properly and repeatedly.  
         [0031]     The wedge slot WS and the wedge shield WSH complete this set of features that make this tamper resistant mechanism work properly. The particular design of this variation of wedge may respond to the fact that a wedge may transmit a movement with two perpendicular directions. In this case, when the cartridge  20  is inserted into the docking station DS of the portable computing device, as shown in  FIG. 1 , there may be a feature in the portable computing device  10  with a wedge type design. That wedge may be aligned with the slot WS of the cartridge  20  and the corresponding slot of the sliding door  24 . By inserting the cartridge  20  farther, the wedge penetrates the slot WS and forces the sliding door  24  to move in a perpendicular direction of the cartridge insertion (i.e., sliding door  24  moving far away from the spring holder SH, so the fuel path is cleared and the corresponding computing device valve can couple with the cartridge valve and inside components therefrom). Once the variation of the wedge of the computing device penetrates the slot WS, there is a shield WSH in the cartridge that may act as a backstop to protect the internal components of the cartridge and impede any improper access to the inside of the cartridge, which may comprise, but not limited to, a flexible fuel container or liner, and fuel (i.e., methanol). In addition, the double wall that houses the sliding door  24  and creates the door housing DH may also protect the inside components of the cartridge  20  when the door  24  slides from side to side.  
         [0032]     This variation of the bottom housing  23  may be manufactured out of plastic materials, such as polycarbonate, for example, which may provide robustness and resistance to impact under certain situations, such as, but not limited to, added compression force (i.e., a person stepping onto the cartridge) or a drop or fall from a considerable height. The manufacturing process used may be plastic injection molding. The overall external dimensions for this variation of bottom housing  23  may be: 75 mm long (10 mm for the tamper resistant feature, added to 65 mm long for a variation of a non-tamper resistant cartridge, for example), 75 mm wide, and 10 mm high. It can be inferred that the only dimension that may be affected by this variation of tamper resistant feature is the length of the cartridge or the dimension in the same directions of the insertions of the cartridge into the docking station DS of the computing device  10 . This consideration may also apply to this variation of top housing  22 , with identical form factor as the bottom housing  23 . The only features that are not contemplated on the top housing  22  are the spring holder SH and the spring post SP, which are only featured in this variation of bottom housing  23 .  
         [0033]     The variation of sliding door  24 , as shown in  FIG. 5A , presents various mechanical features: hole SDH, spring post SDSP, guiding ridges GR, wedge slot SDWS, and chamfer CH. In this variation, the hole SDH may be slightly larger than that of the valve to allow for greater tolerances in manufacturing, so its diameter may be between 5 to 10 mm. It can also be chamfered to assist in valve insertion. The spring post SDSP, with approximately the same dimensions of its corresponding end of the spring holder SH of the door housing DH of the bottom housing  23 , holds one spring hook of the variation of spring  25 , and may have a wider diameter at the top to keep the spring  25  from slipping off the post SDSP. This variation of sliding door  24  may have some guiding features GR, as shown in  FIG. 5A . The thickness of such guiding features GR may be approximately 1 mm thicker than the sliding door  24  thickness, so the area of friction may be reduced and the performance of the tamper resistance mechanism improved. The number of guiding features GR varies with the dimension of the sliding door  24 . For a variation of sliding door  24  with a length over 25 mm, it may be recommended to have 6 guiding features GR distributed equally on top and bottom of the sliding door  24 , as shown in  FIG. 5A . These features GR may be chamfered or with a certain radius so sharp edges are avoided. The wedge slot SDWS may be chamfered CH so when the cartridge  20  is engaging with the wedge feature of the portable computing device  10 , the door  24  can be opened by moving sidewise in a perpendicular direction of the connection of the cartridge  20  with the computing device  10 . Therefore, the door  24  moves so the fuel path is cleared and the computing device valve can penetrate the hole SDH and connect with the corresponding cartridge valve. The thickness of the sliding door  24  may be between 3 to 10 mm, and material robustness may be required to withstand the opposing force of the wedge feature of the computing device  10 . The manufacturing process to obtain this variation of sliding door  24  and the materials used may be the same of those used for this variation of top housing  22  and bottom housing  23 . A more cost effective solution may be the variation of sliding door  24  presented in  FIG. 5B , where the amount of material have been reduced, corners have been rounded, and the spring post SDSP have been reinforced by rounding the edge RR, as shown in  FIG. 5B .  
         [0034]     The assembly of this variation of tamper resistant mechanism described herein may be presented as follows: first, all additional materials, components and sub-components of the cartridge  20  need to be already assemble in place; second, the spring  25  is attached to the door and housing by inserting the to end hooks of the spring  25  into the spring posts SP and SDSP, of the spring holder SH and the sliding door  24 , respectively; thirdly, the door is let sit onto the door housing DH chamber; lastly, top housing  22  and bottom housing  23  may be secured and joint together by using ultrasonic welded process. Ultimately, the complete manufacturing operation for this variation of the fuel cartridge  20  may be finished when fuel cartridge  20  is filled with fuel with the specified volume for the cartridge  20 .  
         [0035]      FIG. 6A  and  FIG. 6B  show a connecting sequence stage between the portable computing device  10  (represented by an L-shaped component, as shown in  FIG. 6A ) and a variation of the tamper resistant fuel cartridge  20 , where the door  24  is in “open” position. Therefore, the cartridge  20  is fully engaged with the computing device  10 ; the wedge feature W of the computing device  10  is totally inserted into the wedge shield WSH of the housing through the wedge slot WS; the sliding door  24  is pushed sideways to its maximum position; the axis hole SDH of the sliding door  24  is aligned with the valve neck orifice VNO (as shown in  FIG. 6B ) of the housing (top and bottom housings); the spring  25  is expanded to its maximum position; and the device valve of the computing device  10  can now penetrate through the orifice VNO connecting with its corresponding valve of the fuel cartridge  20 . The operating mode of this variation of spring  25  may be extension mode, which may indicate that the spring  25  is in relaxed position when the door  24  is closed and it may be extended when the door  24  is opening, reaching its maximum position or extension rate when the door  24  is open. Once the cartridge  20  is disengaging from the docking station DS of the portable computing device  10 , the spring  25  may force the door  24  return to its original and “natural” position, with the door  24  in “closed” position.  
         [0036]      FIG. 7A  and  FIG. 7B  show a connecting sequence stage between the portable computing device  10  (represented by an L-shaped component, as shown in  FIG. 7A ) and this variation of the tamper resistant fuel cartridge  20 , where the door  24  is in “closed” position. In this stage, the cartridge  20  is totally disengaged from the computing device  20 ; the spring  25  is in “relaxed” position, so there may not be any spring related force applied to the sliding door  24 , which may be also in “relaxed” position; the axis hole SDH of the sliding door  24  is no longer aligned with the valve neck orifice VNO and the hole SDH may not be seen from the exterior of the cartridge  20 .  
         [0037]     Once the top housing  22  and bottom housing  23  are modified with all the mechanical features needed to operate this tamper resistant mechanism, only two parts may be required: sliding door  24  and a spring  25 . This spring  25  can be purchased from standard stock and this variation of sliding door  24  may be made out of plastic materials, which can be manufactured by regular and inexpensive plastic injection molding process. Such as design is robust, easily scaled, and is difficult to bypass without tools. The design does generate some friction, and will require some force to fully insert properly. Also, the receiving side can be configured with a lock to hold the cartridge in place. Such an arrangement allows for the delivery of fuel from cartridge  20  in any orientation.  
         [0038]     An alternative variation to this tamper resistant solution presented is shown in  FIG. 8 . The added features and components are the sliding door  26  with a new feature or rotating door slot RDS and a rotating door  27 . These two new components, in reference to the above mentioned tamper resistant solution, may be manufactured with, but not limited to, polycarbonate, a blend of polycarbonate with ABS, polycarbonate with a certain percentage of glass fiber (no more than 20%), polypropylene, or LDPE (low density polyethylene).  
         [0039]      FIG. 9A  and  FIG. 9B  show an isometric view and a top view, respectively, of a variation of the sliding door mechanism  40  when this mechanism is in “open” position and a portable device (i.e., notebook computer) is in “engaged” position. Therefore, the cartridge  20  is fully engaged with the computing device  10 ; the wedge feature W of the computing device  10  is totally inserted into the wedge shield WSH of the housing through the wedge slot WS; the sliding door  26  is pushed sideways to its maximum position; the rotating door  27  rotates around its axis in such way that the rotating door post RDP travels through the rotating door slot RDS of the sliding door  26 ; the axis of hole SDH of the sliding door  26 , the axis of the rotating door hole RDH, and the axis of the valve neck orifice VNO of the housing are aligned; the spring  25  is expanded to its maximum position; and the device valve of the computing device  10  can now penetrate through the orifices VNO, SDH and RDH connecting with its corresponding valve of the fuel cartridge  20 . This variation of spring  25  could eventually be replaced by a torsion spring with the torsion coils concentric with the rotating door  27 , although that configuration may add some complications to the assembly and performance. The guiding features GR are also added to this alternative variation of tamper resistant mechanism  40 . The shape of the sliding door  26  may change so it accommodates better the rotating door  27  and does not add volume to this feature, so the volumetric efficiency of the tamper resistant cartridge  20  may be increased. This variation of the rotating door  27  may have some features (i.e., bumps) to reduce the surface contact with the sliding door  26  so the friction effect may be minimized.  
         [0040]      FIG. 10  shows a front view of a variation of the sliding door mechanism  40  when this mechanism is in “semi-open” position. It can be observed how the rotating door post RDP travels through the rotating door slot RDS of the sliding door  26 . The additional value of this alternative variation of sliding door mechanism  40  may be the added difficulty to bypass the mechanism  40  by children without tools.  
         [0041]     Another alternative variation to this tamper resistant solution presented is shown in  FIG. 11 . The added features and components are the external sliding door  44  with new features, the door actuator  45 , a return spring  43 , and some modifications to the features of the top housing  41  and the bottom housing  43 . These three new components, in reference to the above mentioned tamper resistant solution, may be manufactured with, but not limited to, polycarbonate, a blend of polycarbonate with ABS, polycarbonate with a certain percentage of glass fiber (no more than 20%), polypropylene, or LDPE (low density polyethylene).  
         [0042]      FIG. 12  show an isometric “open” view of a variation of the sliding door mechanism  46  when this mechanism is in “open” position and a portable device (i.e., notebook computer) is in “engaged” position. Therefore, the cartridge  20  is fully engaged with the computing device  10 ; the wedge feature W of the computing device  10  is totally inserted into the wedge shield WSH of the housing through the wedge slot WS; the sliding door  44  is pushed sideways to its maximum position; the return spring  45  is compressed to its minimum position; the door actuator is pushed down to its maximum position; and the device valve of the computing device  10  can now penetrate through the orifice VNO with its corresponding valve of the fuel cartridge  20 . The guiding features GR are also added to this alternative variation of tamper resistant mechanism  46 . The shape of the sliding door  44  may change so it accommodates better the door actuator  45  and does not add volume to this feature, so the volumetric efficiency of the tamper resistant cartridge  20  may be increased.  
         [0043]      FIG. 13  shows an isometric view of a variation of the sliding door mechanism of the variation of the tamper resistant fuel cartridge of  FIG. 2  when this mechanism is in “closed” position and a portable device (i.e., notebook computer) is not in the “engaged” position. The additional value of this alternative variation of sliding door mechanism  46  may be the added difficulty to bypass the mechanism  46  by child without tools. The sliding door  44  is pushed sideways to its opposite maximum position; the return spring  45  is expanded to its maximum position; the door actuator is returned upwards to its maximum position; and the device valve of the computing device  10  cannot now penetrate through the orifice VNO with its corresponding valve of the fuel cartridge  20  due to inference with the sliding door  44 . The guiding features GR are also added to this alternative variation of tamper resistant mechanism  46 .  
         [0044]     Although a few variations have been described in detail above, other modifications or additions are possible. In particular, further features and/or variations may be provided in addition to those set forth herein. For example, the implementations described above may be directed to various combinations and subcombinations of the disclosed features and/or combinations and subcombinations of several further features disclosed above. Other embodiments may be within the scope of the following claims.