Fuel tank with flange and positioning structure for combustion-powered tool

Abstract

Fuel container (60) which is designed and arranged for use with a combustion-powered tool (10) which has a cylinder head frame, wherein the fuel container comprises: an outer covering (68) with a closed lower end (128) and an open upper end (72); a closure (70) which is crimped over the upper end (72) and defines an opening (74) for receiving a reciprocating valve stem (64); characterized by an adapter (80) which is in frictional engagement with the closure (70) and which has a flange (126) which extends radially beyond the outer casing (68) and is designed to hold the fuel container (60) in a part of the cylinder head frame only by suspending it from that part.

Description

background

[0001] The present invention relates generally to improvements in fuel cell fuel delivery assemblies for use in combustion-powered tools, and more particularly to adapters provided for fuel cells for combustion-powered tools to obtain a more consistent fuel metering.

[0002] In this application, the term "combustion-powered tool" refers to combustion-powered fastener driving tools, also known as combustion-powered nailers, cordless carpentry tools, cordless trimming tools, and the like. More specifically, the present invention relates to improvements in the fuel supply of fuel cells commonly used for such purposes. In this application, the term "fuel cell" refers to a container for holding a fuel, also referred to as a fuel canister.

[0003] Such tools typically have a housing that essentially encloses a combustion energy source, a fuel cell, a battery, a trigger mechanism, and a magazine containing a fastener supply for sequential driving. The energy source has a reciprocating drive blade that separates a leading fastener from the magazine and drives it through a nosepiece into the workpiece. Exemplary tools are described in US patents US 4,483,473 A, US 4,522,162 A, US 6,145,724 A, and US 6,679,414 B2. Such fastener driving tools and fuel cells are commercially available from ITW-Paslode (a division of Illinois Tool Works Inc.) of Vernon Hills, Illinois under their trademark IMPULSE. A generic fuel container is known from EP 1 327 501 A2.Further fuel containers are described in DE 10 2009 008 169 A1, US 7 478 740 B2 and US 2002 004 3547 A1.

[0004] As exemplified in U.S. patents Nos. 4,403,722, 4,483,474, and 5,115,944 to Nikolich, it is known to use a dispensing device, such as a fuel cell, to dispense a hydrocarbon fuel to a combustion-powered tool. A design criterion of such fuel cells is that only a desired amount of fuel, or fuel dose, should be dispensed by the fuel cell for each combustion event. The amount of fuel should be carefully controlled to deliver the desired combustion, yet in a fuel-efficient manner to extend the operating life of the fuel cell.

[0005] Previous attempts to address this dosing factor have resulted in fuel dosing valves being located in the tool (US Patent US 5 263 439 A) or attached to the fuel cell (US Patent US 6 302 297 B1). Fuel cells have been introduced with built-in dosing valves, as in the US patent).

[0006] Regardless of the metering valve arrangement, the associated combustion-powered nailer is designed to exert a force on the valve, either on the reciprocating valve stem or the valve body itself, to cause the stem to retract against a biasing force in the metering valve to deliver a metered fuel dose. It is important for the fuel balance in the fuel cell and for the desired operation of the combustion-powered nailer that only the specified amount of fuel is delivered to the tool on a metered basis.

[0007] However, variations in manufacturing tolerances often lead to tolerance buildup, which under certain circumstances can disrupt the engineered connection between the fuel cell and the tool, as well as the tool's fuel actuation mechanism, which depresses the fuel cell valve stem before each combustion cycle receives the desired fuel dosage for combustion. Therefore, there is a need for a combustion-powered tool that delivers a consistent fuel supply while accommodating the tolerance buildup inherent in the manufacturing of combustion-powered tools. Summary

[0008] The aforementioned manufacturing problem of tolerance buildup is addressed in the present fuel cell for a combustion-powered tool and its associated tool. To more precisely maintain the relationship between the fuel cell metering valve stem and the corresponding actuating mechanism, the fuel cell is suspended from arms on the cylinder head rather than resting on a floor within the fuel cell chamber of the tool housing. This results in a more consistent relationship between the fuel cell and the corresponding tool actuating mechanism.

[0009] Additionally, an upper end of the fuel cell adapter is provided with a vertically protruding cylindrical formation that forms a face seal with a corresponding receiving portion of a shaft receiver block. This improved design results in a more positive seal that accommodates the tolerance buildup described above, as well as severe vibration shocks inherent in normal combustion-powered tool operation.

[0010] More specifically, a fuel cell is provided, constructed, and arranged for use with a combustion-powered tool having a cylinder head frame. The fuel cell includes an outer enclosure with a closed lower end and an open upper end, and a closure crimped over the upper end and defining an opening for receiving a reciprocating valve stem. An adapter friction-fits the closure and includes a flange configured to suspend the fuel cell within the fuel cell chamber.

[0011] In another embodiment, a combustion-powered tool is provided having a housing containing a combustion energy source including a cylinder head, the cylinder head being provided with a frame having a pair of spaced-apart parallel arms defining therebetween a fuel cell chamber having a floor defined by the housing, each of the arms defining a locating shoulder on an interior surface. A fuel cell is configured for releasable insertion into the fuel cell chamber and has an adapter, the adapter having a flange configured to engage the locating shoulder for suspending the fuel cell in the fuel cell chamber such that a bottom surface of the fuel cell is spaced from the floor.

[0012] In yet another embodiment, an internal combustion tool is provided having a housing containing a combustion energy source, including a cylinder head, the cylinder head defining a combustion chamber. A fuel cell is adapted for releasable insertion into the fuel cell chamber and has an adapter. A fuel line is in communication with the combustion chamber and has a free end connected to a stem receiver block having an internal passageway. The adapter is adapted for connection to the stem receiver block and includes a hub adapted for mating engagement with the block, 20 and has a cylindrical extension projecting from an upper end to form a face seal with the stem receiver block. Short description of the drawings Fig. 1 is a front perspective view of a combustion-powered tool equipped with the present fuel cell positioning system; Fig. 2 is a partial perspective view of the tool of Fig. 1, which shows the fuel cell door open to accommodate a fuel cell; Fig. 3 is a partial vertical section of the tool of Fig. 2; Fig. 4 is a bottom perspective view of the present fuel cell provided with a positioning flange for suspended engagement with the combustion chamber frame; Fig. 5 is a perspective top view of the present fuel cell equipped with the present positioning flange adapter and Fig. 6 is a partial vertical section of the present fuel cell connected to the present combustion-powered tool. Detailed description

[0013] With reference to the Fig. 1 to 3, a combustion-powered nailing tool is shown, generally designated 10. As is known in the art, a main tool housing 12 encloses a power source 14 and a fuel cell chamber 16. A fuel cell door 18 is pivotally engaged on the housing 12 and is configured to close the fuel cell chamber 16 during tool operation. The construction and arrangement of such doors 18 are well known in the art.

[0014] The energy source 14 has a reciprocating piston 20 ( Fig. 3) with a driver blade 22 attached thereto for joint movement relative to the energy source and in a cylinder 24. A nose piece 26 ( Fig. 1) is attached to a lower end of the power source 14, as is known in the art, and provides an attachment point for a fastener magazine 28, shown here as a reel magazine, although other types of magazines, such as strip magazines, are also contemplated. Fasteners are sequentially fed from the magazine 28 into the nosepiece 26, where they engage the driver blade 22 and move downwardly into a fastener passageway in the nosepiece.

[0015] The fasteners are driven into a workpiece or substrate upon initiation of a work cycle, which in some tools is started by the operator actuating a trigger 30. A workpiece contact element 32 moves back and forth relative to the nosepiece 26 to control the tool functions, as is known in the art but not relevant to the present discussion.

[0016] The housing 12 also has a handle 34 which serves as an attachment point for the trigger 30. A battery chamber 36 ( Fig. 1) is also provided on the housing 12 for receiving at least one battery 38 for operating electronic tool functions such as spark generation, cooling fan operation, electronic fuel injection and / or tool condition sensing, as known in the art.

[0017] With reference to the Fig. 2 to 4, an upper end of the energy source 14 is defined by a cylinder head 40, which serves as a mounting point for a blower motor 42, which drives a fan 44, which projects into a combustion chamber 46, and is also the mounting point for a spark generator or spark plug 48. Also provided on the cylinder head 40 are two spaced parallel arms 50, each having a recessed positioning shoulder 52, which is provided on an inner surface 54 ( Fig. 2). A space 56 between the inner surfaces 54 defines an entrance to the fuel cell chamber 16. The entrance 56 is considered part of the fuel cell chamber 16. The ends of the arms 50 have pivot openings 57 for receiving corresponding projections 58 of the fuel cell door 18.

[0018] With reference to the Fig. 3 to 6, as described in US Patent US 5 263 439 A, a fuel cell is inserted into the fuel cell chamber 16, which fuel cell is generally designated 60, the general construction of which is well known in the art of combustion-powered tools, and which is designed for releasable engagement with the fuel cell chamber 16. The particular construction of the present fuel cell 60, which has a built-in fuel metering valve 62 ( Fig. 3 and Fig. 6), is described in co-pending US patent US 7,392,922 B2. Generally speaking, a fuel valve stem 64 is biased to a closed position, such as by a spring (not shown), but when axially depressed, a metered dose of fuel is dispensed. Upon withdrawal of the axial force, the stem 64 returns to its rest position, and a subsequent dose of fuel flows into a metering chamber 66 for the next power stroke.

[0019] Other major components of the fuel cell 60 include a generally cylindrical, closed-bottom outer enclosure 68 and a closure 70 crimped over an open upper end 72 of the enclosure. The closure includes an opening 74 for receiving the reciprocating valve stem 64.

[0020] With reference to the Fig. 4 to 6, an important feature of the present fuel cell 60 is an adapter, generally designated 80. A major portion of the adapter 80 is the adapter body 82, which is generally cylindrical in shape and sized to fit snugly within a peripheral annular ring 84 formed by the fuel cell closure 70. A close frictional fit of the adapter 80 within the closure 70 is enhanced by at least one radially extending gripping formation 86 defining an annular groove 88 for tightly engaging the ring 84. The formation 86 may be provided as a single closed ring or a series of spaced-apart protrusions.

[0021] To reduce the possibility of a user inadvertently using a fuel cell that is not equipped with a built-in metering valve 62, the adapter 80 is designed to be extremely difficult to remove from the closure 70. This is achieved by sizing the gripping formation 86 and the groove 88 to provide a very tight friction fit with the closure 70. Furthermore, by preferably molding the adapter 80 from a plastic material, a material is selected for rigidity, as well as fuel resistance, formability, and durability. It is contemplated that acetyl, commonly sold under the trademark Celcon.RTM by Hoechst Celanese, Charlotte, NC, is a preferred material, however, other acetyls, polyamides, or other fuel-resistant plastics may be suitable.

[0022] An upper portion 90 of the adapter body 82 defines a positioning ring 92 having an upper open end 94 for receiving a shaft receiver block 96 ( Fig. 30 6). An inner chamber 98 is defined within the adapter 80 by the body 82 and is provided with a hub 100 which is reciprocally movable relative to the adapter body and has a first lower end 102 adapted for operative engagement and fluid communication with the valve stem 64 and to have a larger diameter inner bore 104 in communication with a fuel passage bore 106. The inner bore 104 has a chamber 105 adapted to closely and slidably receive the valve stem 64. The fuel passage bore 106 is also in fluid communication with the valve stem 64 as well as with an internal passage 108 in the stem receiver block 96.

[0023] Also located on the first hub end 102 is an annular base 110, which acts as a stop on the fuel cell closure 70. This stop is important in limiting the amount of depression of the valve stem 64 by actuation of an actuator 112 on the fuel cell door 18 or another vertical force. Excessive depression of the stem 64 can cause more than the predetermined fuel dose to be delivered and should be avoided.

[0024] A second upper, generally cartridge-shaped end 114 of the hub 100, opposite the first end 102, is adapted to engage and be in sealed fluid communication with the stem receiver block 96. The second end 114 of the hub 100 and a hub cavity 116 in the block 96 are complementarily formed to have a close friction fit. This close fit facilitates the physical connection between the hub 100 and the block 96 and maintains a sealing relationship to prevent fuel leakage. Further details of the stem receiver block 96 and the hub 100 and other parts of the adapter 80 are described in U.S. Patent No. 7,654,429 B2.

[0025] In addition to this complementary, corresponding fit, it is preferred that the second hub end 114 be provided with a tubular cylindrical extension or projection 118, which forms a face seal with an upper planar end 120 of the hub cavity 116. This face seal provides sufficient complementary surface area between the hub 100 and the stem receiver block 96 to provide a positive sealing relationship. Furthermore, the projection 118 has a sufficient axial length with fairly close tolerances with a cylindrical locating recess 122 to maintain the face seal perpendicular.

[0026] A feature of the adapter 80 is that the hub 100 is reciprocable relative to the body 82 so that the hub can follow the cyclical movement of the valve stem 64. Therefore, the hub 100 accommodates the movement induced in the system by the actuator 112 as well as by the spring in the fuel cell 60. In the preferred embodiment, the reciprocating movement is provided by at least one curved flexible member 124 attached at a first end to the adapter body 82 and at an opposite end to the hub 100. The flexible members 124 are designed to add only a minor force to that required to urge the fuel valve stem 64 into the fuel cell 60. In construction, the flexible members 124 are spiral-shaped and have a generally circular cross-section to improve flexibility while reducing torsional stiffness.

[0027] There are preferably three curved flexible elements 124 and they substantially suspend the hub 100 relative to the body 82. In addition to the suspension function, the flexible elements 124 bias the hub 100 into a rest position which is Fig. 6 is shown.

[0028] Again with reference to the Fig. 4 to 6, the adapter body 82 is also provided with a flange 126 which is designed to engage the positioning shoulders 52 for suspending the fuel cell 60 in the fuel cell chamber 16. It can be seen that the generally planar flange 126 defines a circular disk shape and extends beyond an outer surface of the outer enclosure 68 of the fuel cell. In fact, the flange 126 is sized such that once engaged with the positioning shoulders 52, it is the only support for the fuel cell 60 in the fuel cell chamber 16. More specifically, once suspended from the shoulders 52, a floor 128 of the fuel cell 60 is above and clear of the floor 130 of the fuel cell chamber 16 ( Fig. 3). While the particular engagement of flange 126 is described in paragraphs 52 herein, it is contemplated that adapter 80 may be provided with alternate structures designed to suspend fuel cell 60 from cylinder head 40.

[0029] The flange 126 is preferably generally coplanar with the hub 100 and extends radially from the upper portion 90 of the adapter 80 between the axially extending actuator ring 92 and a generally central lip 132 extending radially from the adapter body 82 and resting on the circumferential locking ring 84. In particular, the flange 126 is disposed between the actuator ring 92 and the curved flexible member 124.

[0030] With reference to the Fig. 2, Fig. 3 and Fig. 6, the stem receiver block 96 is connected to a free end 134 of a fuel line 136, the opposite end of which is in fluid communication with the combustion chamber 46. As is known in the art, a fuel cell actuator assembly is provided for delivering a fuel dose from the fuel cell 60 through the fuel line 136 and is generally designated 138 and is in operative relationship with the fuel cell chamber 16 and is constructed and arranged to exert an axial force on the valve stem 64. A major component of the actuator 138 is the generally elongated actuator member 1112, which is configured to exert an axial force on the stem 64, thereby releasing the fuel dose. In the preferred embodiment, member 112 is associated with the fuel cell door 18 and is in actual contact with the stem receiver block 96.

[0031] As in Fig.3, the fuel cell door 18 is pivotally engaged with pivot points 57 on the cylinder head arms 50. As is well known in the art of combustion-powered tools, vertical projections 140 on the reciprocating valve sleeve 142 (which substantially defines the combustion chamber 46) engage the ends 144 of the actuator member 112 and cause it to rock relative to the fuel cell door 18, thus exerting the periodic axial force on the stem receiver block 96, which in turn axially depresses the valve stem 64. Once the tool 10 is pressed against a workpiece and the workpiece contact member 32 is retracted relative to the cylinder 24, ultimately causing the valve stem 64 to depress, a dose of fuel is released into the combustion chamber 46, resulting in combustion or firing of the tool 10.

[0032] Therefore, it can be seen that the present fuel cell 60 equipped with the present adapter 80 is more convenient for manufacturing than previous designs in that tolerance buildup is no longer a problem by maintaining a positive sealing engagement between the fuel cell valve stem 64 and the stem receiver block 96. Also, by suspending the fuel cell 60 from the cylinder head arms 50, more constant positioning of the fuel cell is achieved.

[0033] While a particular embodiment of the present flanged fuel cell and positioning structure for a combustion tool has been illustrated and described, one skilled in the art will appreciate that changes and modifications may be made without departing from the invention in its broader aspects and as set forth in the following claims.

Claims

[1] A fuel container (60) constructed and arranged for use with a combustion-powered tool (10) having a cylinder head frame, the fuel container comprising: an outer shell (68) having a closed lower end (128) and an open upper end (72); a closure (70) crimped over the upper end (72) and defining an opening (74) for receiving a reciprocating valve stem (64); characterized by an adapter (80) which is in frictional engagement with the closure (70) and which has a flange (126) which extends radially beyond the outer casing (68) and is adapted to hold the fuel container (60) in a part of the cylinder head frame only by hanging from the part. [2] The fuel container of claim 1, wherein the adapter (80) further comprises a hub (100) generally vertically reciprocable relative to the adapter (80) and having a first end sized to frictionally engage the valve stem (64) and define an internal bore (106) in fluid communication with the valve stem (64), the flange (126) being generally coplanar with the hub (100). [3] The fuel container of claim 1, wherein the flange (126) extends radially from an upper end of the adapter (80). [4] The fuel container of claim 2, wherein the adapter (80) further comprises an actuator ring (92) extending beyond a top surface of the flange (126) and defining an inlet into an interior chamber (98). [5] The fuel container of claim 4, wherein the adapter (80) further comprises a hub (100) generally vertically reciprocable relative to the adapter (80) and having a first end sized to frictionally engage the valve stem (64) and define an internal bore (106) in fluid communication with the valve stem (64), the adapter (80) comprising a curved flexible member (124) mounted within an internal adapter chamber (98) and connected to the hub (100) for accommodating vertical reciprocating movement of the hub, the radially extending flange (126) being disposed between the actuator ring (92) and the flexible member (124). [6] A fuel container according to claim 2, wherein the tool comprises a shaft receiving block (96) adapted to mateably receive the hub (100) and having an internal passage in fluid communication with the internal bore (106), and wherein the hub (100) is provided at an upper end with a cylindrical projection (118) forming a face seal with a complementary portion of the internal passage (108). [7] The fuel container of claim 1, further comprising a hub (100) having a vertical through-bore (106) connected at a lower end to the valve stem (64) and having a generally cartridge-shaped upper end (114) with a cylindrical extension (118). [8] Combustion-powered tool, comprising: a housing (12) enclosing a combustion energy source (14) including a cylinder head (40); wherein the cylinder head (40) is provided with a frame having a pair of spaced parallel arms (50) defining therebetween a fuel reservoir chamber (16) with a bottom defined by the housing (12), wherein each of the arms (50) defines a positioning shoulder (52) on an inner surface; a fuel container (60) adapted for releasable insertion into the fuel container chamber (16) and having an adapter (80); characterized by that the adapter (80) has a flange (126) which is designed to engage with the positioning shoulder (52) for suspending the fuel container in the fuel container chamber (16) so that a bottom of the fuel container (60) is away from the floor, and the fuel container (60) is held in the fuel container chamber (16) only by being suspended from the arms (50). [9] The tool of claim 8, further comprising a fuel line (136) in communication with the combustion chamber (46) and having a free end connected to a stem receiver block (96) having an internal passage (108), and wherein the adapter (80) is adapted to be connected to the stem receiver block (96) and has a hub (100) adapted to mateably engage the stem receiver block (96) and has a cylindrical extension (118) projecting from an upper end to form a seal with the stem receiver block (96). [10] The tool of claim 9, wherein the shank receiving block (96) defines an internal passage (108), and the cylindrical extension (118) is constructed and arranged such that the molded seal is a face seal with the shank receiving block (96).

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