2.1 The Patent
6 The judgment pellucidly distills the complex subject matter of the Patent, the evidence and the dispute into a comprehensive, but short and easily comprehensible analysis of the real issues. The primary judge summarises the background and prior art as follows:
12 The background to the invention is discussed in the first eight paragraphs of the Patent.
13 That section of the Patent first states that the invention relates generally to improvements in fuel cell delivery arrangements for use in combustion tools, and more specifically to metering valves used with such fuel cells for delivering the appropriate amount of fuel for use by a combustion tool during the driving of fasteners. It also explains that while the Patent focusses on fuel cells in combustion tools, the invention may also be applied to other pressurised containers using stem valves, such as those used in relation to cosmetics and pharmaceutical products.
14 The Patent refers to four US prior art patent specifications, each of which are said to be incorporated by reference into the Patent. One of these, US patent No 5,115,944, is later in the specification said to disclose the general construction of fuel cells. The prior art specifications disclose the use of mechanical or electronic valve assemblies designed to be able to control the amount of fuel that is dispensed from the fuel cell into the tool during each operation.
15 The Patent lists a number of "design criteria" it says are relevant to the design of fuel cells containing separate compartments of pressurised fuel and propellant.
16 First, the Patent refers to the prevention or minimisation of leakage of fuel and/or propellant. In particular, a stated objective is to prevent or minimise leakage of fuel and/or propellant after production and before use, also known as shelf life, and during periods when the fuel cell is installed in the tool but the tool is stored or otherwise not in use. The Patent notes that as with other aerosol or fuel canisters, a certain amount of leakage occurs over time. However, there is a concern that gradual leakage over a prolonged shelf life may result in reduced performance of the fuel cell due to insufficient propellant and/or fuel remaining for expected performance needs.
17 A second stated objective of the Patent is that only a desired amount of fuel should be emitted by the fuel cell for each combustion event.
18 The Patent refers to two further US patent specifications: US patent no 5,263,439, which discloses an internal-tool metering valve (where the metering valve is located internal to the tool housing and external to the fuel cell); and US patent no 6,307,297, which discloses an external metering valve (where the metering valve is "attached to the fuel cell" prior to the fuel cell being inserted into the tool housing). These metering valves are designed to control the amount of fuel emitted each time, for example, a nail gun is fired. These two additional specifications are also said to be incorporated by reference into the Patent.
19 The Patent emphasises that regardless of where the fuel metering valve is located, fuel leakage has remained a design consideration. In this context, it states that internal tool fuel metering valves have the disadvantage of requiring an excessive number of seal locations, which, in turn, provides more opportunities for fuel leaks. In order to facilitate disposability of external fuel cell metering valves, inexpensive materials are used. However, the aggressive nature of the fuel constituents may in some cases cause premature failure of the valve seals or the valve housing itself.
20 Another design consideration is said to be to avoid the duplication of components associated with external fuel cell metering valves, in that a first valve controls the flow of fuel from the cell, and a second valve controls a metered dose of fuel for delivery to the tool for a single combustion event. A related concern is the shipping of external fuel cell metering valves. The valves are shipped in an inoperative position and must be activated by the user by moving the valve into position. Fuel leakage from improper installation of the metering valve is a problem.
21 A further design consideration associated with cell-mounted metering valves is said to be that once the valve is operationally installed, the main cell stem valve is continuously open. The nature of the seal formed by the main fuel cell valve stem seal changes from a face seal to a radial seal about the valve stem, a more relaxed seal which proves less effective sealing and increases the potential for leakage.
7 The primary judge then refers to the summary of the invention and notes that against the background summarised above, including the incorporated prior art specifications, the invention disclosed in the Patent provides a fuel cell for use with a combustion tool which includes an internal metering valve, arranged such that a measured dose of fuel is dispensed each time the stem is depressed into the "open" position. The invention disclosed facilitates one or more of the fuel seals in the prior art internal-tool or external metering valves, which may have contributed to the total amount of leakage from the device, to be "designed out". This has been done, the primary judge finds, by structurally changing the device so that the metering valve is located within the fuel cell housing, which in turn reduces the number of component connections and streamlines the flow of the fuel between the fuel housing and the tool. In addition, the primary judge notes that the disclosure of the invention provides that by locating the metering valve inside the fuel cell, the invention combines in a single unit the functions of two valves in the prior art fuel cells. It thereby reduces duplication of components, as the invention only requires one valve body, one biasing element (eg a spring) and one stem, and reduces the overall number of required seals compared to the prior art discussed in the Patent, which is said to reduce cost, increase reliability and make the invention more user friendly.
8 After referring to the description of 14 exemplary embodiments identified in the patent at [8a] to [8n], the primary judge refers to the description of the preferred embodiment, which features a metering valve internally mounted in the fuel cell, defined by a one-piece valve body, one end of which is located inside the inner fuel container located within the fuel cell. Her Honour notes at [27] that:
…it is by locating the metering valve inside the fuel cell housing (or can) that the valve usefully combines in a single unit the functions of the Prior Art standard fuel cell "check valve" and separate "external metering valve".
9 The primary judge then refers to the detailed description of the invention provided in the Patent, setting out Figure 1 (which, we interpolate, is described in the Patent as a split vertical cross-section of a combustion tool fuel cell provided with the present internal metering valve, shown in closed (left) and open (right) positions) as follows:
10 The primary judge provides a description as follows at [30]:
In the brief summary section, the Patent explains that the function of the fuel metering chamber (38) is to facilitate the storage and subsequent dispensation of a measured amount of fuel through the outlet of the fuel cell. In the preferred embodiment depicted in Fig 1, the fuel metering chamber engages an outlet seal, which is adjacent to the closure (16) of the fuel cell. However, the Patent explains that the fuel metering chamber may be located within the housing and is preferably located within the valve body (34) and in close proximity to the closure. Locations external of the valve body (34) are also expressly contemplated.
11 The primary judge then sets out the following paragraphs of the Patent, which were referred to in argument before her in the context of the construction of the second end opposite integer (emphasis added by the primary judge):
[20] A main valve stem 26 is configured for emitting fuel from the container 22 and as such has an outlet 28 at a first end 30 projecting from the housing, and a second end 31 opposite the first end. The valve stem 26 is in fluid communication with the source of fuel, preferably the container 22, which is preferably flexible or compressible to accommodate pressure exerted by the propellant as fuel is consumed and the volume of the container accordingly reduced. The first and second ends 30, 31 are separated from each other, preferably by a passageway 32. To emit fuel, the main valve stem 26 reciprocates relative to the housing 12 within a valve body 34 under a biasing force, preferably exerted by a biasing element 36 such as a spring, between a closed position (shown on the left half of FIG. 1) and an open position (shown on the right half of FIG. 1). In the closed position, the main valve stem 26 is biased by the biasing element 36 to an extended condition. In the open position, the main valve stem 26 is pushed back or retracted in a way that overcomes the biasing force of the element 36.
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[22] In the embodiment of FIGs. 1 and 2, the fuel metering valve 25 includes a fuel metering chamber 38 located within the housing 12. This configuration is intended to reduce components and/or to reduce unwanted leakage or emission of fuel, which are design issues with current fuel cells. Preferably, the fuel metering chamber 38 is located within the valve body 34, and more preferably in close proximity to the closure 16, however locations externally of the valve body are also contemplated. By incorporating the metering valve 25 so that the valve body 34 is located permanently inside the fuel cell 10, potential leakage areas at the engagement point of an external valve to the prior art main valve stem are eliminated. Also, potential dosage changes due to environmentally or hydrocarbon exposure-caused changes in external metering valve dimensions are also eliminated.
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[25] In the closed position, the inlet 48 is no longer located within the fuel metering chamber 38, and is preferably external of the seal 42. Thus, in this position, fuel cannot enter the main valve stem 26. The at least one stop member 50 is positioned on the main valve stem 26 so that it engages the outlet seal 42 and prevents further movement of the valve stem past the closure 16. Another feature of the main valve stem 26 is a generally radially enlarged portion 52. The enlarged portion 52 is of sufficient diameter to sealingly engage the lip seal 46 and prevent the passage of fuel into or out of the entry of fuel relative to the fuel metering chamber 38. A standard or relatively narrow diameter portion 54 of the main valve stem 26 is located between the stop 50 and the enlarged portion 52. At the opposite end, the generally enlarged portion 52 gradually reduces in diameter to form a seat 56 for the biasing element 36. An opposite end of the biasing element 36 engages an end of a body cavity 60 in the main valve body 34 in which reciprocates the main valve stem 26.
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[27] To facilitate the delivery of fuel to the metering chamber 38, the valve body 34 is secured to the container 22, preferably such that the valve body has a first end 66 engaging the closure 16, such as by being crimped, and the second end 62 having the nipple portion located within the container. It will be seen that the biasing element 36 is located in the valve body 34 between the second end 62 and the first end 66, the latter providing the location for the fuel metering chamber 38, which is opposite the second end 62. It is contemplated that variations of this disposition of the valve body 34 are suitable for achieving the goal of secure mounting of the valve body relative to the fuel cell 10 for support and for consistent fuel metering during tool operation.