Sabaf SpA v MFI Furniture Centres Ltd

JurisdictionEngland & Wales
CourtCourt of Appeal
Judgment Date11 Jul 2002
Neutral Citation[2002] EWCA Civ 976
Docket NumberCase No: CHPCF/2001/2175/A3

[2002] EWCA Civ 976





Laddie J.

Royal Courts of Justice


London, WC2A 2LL


Lord Justice Peter Gibson

Lord Justice Jonathan Parker and

Lord Justice Longmore

Case No: CHPCF/2001/2175/A3

Sabaf SPA
Mfi Furniture Centres and Another

Mr. Simon Thorley Q.C. and Mr. Mark Vanhegan (instructed by Messrs Field Fisher Waterhouse of London) for the Appellant

Mr. Alastair Wilson Q.C. and Mr. Peter Colley (instructed by Messrs Middleton Potts of London) for the Respondents

Peter Gibson L.J. (giving the judgment of the court):


This is an appeal in a patent infringement case. Laddie J. on 25 September 2001 dismissed the action brought by the Claimant, SABAF SpA ("SABAF"), the registered proprietor of a patent, against the Second Defendant, Meneghetti SpA ("Meneghetti").


The patent in suit, GB 2,100,411C, is in respect of burners for gas hobs. It was applied for on 12 June 1981 and it expired 20 years later. SABAF is an Italian company, as is Meneghetti. Meneghetti in Italy manufactured burners which it sold to the First Defendant, MFI Furniture Centres Ltd. ("MFI"). Meneghetti's burners were imported into this country for sale by MFI in its retail stores. On 15 February 2000 SABAF commenced this action, alleging infringement of its patent by MFI and Meneghetti, who, SABAF said, committed infringing acts within the jurisdiction by importing its burners and by being a joint tortfeasor with MFI. SABAF settled its claim against MFI, which took no part in the proceedings. At the trial before the judge Meneghetti contended that the patent was invalid, that its burners do not fall within the scope of the patent, and that it had not infringed the patent, whilst in force, by doing any infringing act within the jurisdiction. It denied being the importer of the burners and being a joint tortfeasor with MFI. The judge held that Meneghetti's burners did fall within the scope of the patent, and that Meneghetti did infringing acts within the jurisdiction by importing its burners from November 1998 onwards; but he dismissed SABAF's claim that Meneghetti was a joint tortfeasor with MFI, and he held that the patent was invalid for obviousness, there being at the heart of the alleged invention the mere collocation of two well-known concepts.


SABAF now appeals with the permission of the judge on the two points on which it failed. In this court it argues that the patent was not invalid, and also it repeats its claim that Meneghetti was a joint tortfeasor with MFI. Meneghetti, with the judge's permission, cross-appeals on two points on which it was not successful before the judge: it contends that its burners did not infringe the patent because one feature of the claims in the patent is not to be found in its burners, and that it was not the importer of the burners and so did no infringing act within the UK.

The facts


The facts were set out comprehensively and lucidly by the judge and we need only refer to the salient facts to make this judgment comprehensible.


As the judge explained, the burning of gas on a kitchen hob involves the reaction of the gas with oxygen from the air. Some air ("secondary air") will come from the atmosphere surrounding the jet of gas leaving the burner, but that may not be capable of supplying sufficient oxygen to the gas. Consequently it has for a long time been normal to pre-mix the gas with air ("primary air") prior to it leaving the burner, so that what comes out of the burner is a mixture which contains sufficient oxygen to ensure that, when ignited in the presence of secondary air surrounding the burner, it burns completely.


Gas can be mixed with primary air in a number of ways of which two are relevant. One is by the use of a simple cylindrical tube such as is found in a Bunsen burner, the gas being mixed inside the tube with primary air drawn in around the gas injector. Provided the tube is sufficiently long, there will be sufficient mixing within it to enable complete combustion. The other way is by use of a Venturi tube. Such a tube typically has a narrowing or throat such that on either side of the throat the walls of the tube widen. Figure A annexed to this judgment illustrates such a tube as used for a gas burner. In the centre of the mouth of the tube is the gas injector. The gas injection causes primary air to be drawn into the mouth of the tube through the opening around the gas injector. At the throat of the tube the gas and air are moving comparatively fast and have high kinetic energy. As the walls of the tube widen out beyond the throat the flow of air and gas slows down, losing kinetic energy. That loss of kinetic energy changes into potential energy, increasing the pressure of the gas and air. That pressure recovery enables the mixed gas to be available at the holes in the burner at a sufficient pressure to force the mixture through the holes to the outside where it can be ignited. As the judge stated, what happens in a Venturi tube is but one example of a general effect: the increase in potential energy, generated by a decrease in kinetic energy, of a gas stream is a general phenomenon. The same effect can occur otherwise than in a Venturi tube, for example when a gas stream leaves a tube and enters a fan-shaped space; the reduction in speed as the gas spreads out is accompanied by an increase in pressure, and the same effect occurs.


With that background we turn to the amended patent. The specification explains the invention in the following terms:


This invention relates to a burner for gas cookers and hobs in general.

Various types of gas burners for cookers and hobs are known, but these have the disadvantage, among others, that they are relatively tall, for which reason they are not suitable or cannot be used for hobs which must have the most compact and flat structure possible.

Furthermore in burners of the known type the channels for the primary air intake always lead downwards, more specifically below the hob, or towards the oven, in the case of cookers provided with an oven, or towards the chamber or in any event towards the intakes provided for the purpose below the hob.

In addition to this the fitting and centering of burners of the known type is rather laborious and difficult, and once fitted the burners have little stability and are therefore susceptible to undue movement.

Thus they are fitted in such a way that access to and dismantling of the needle and gas injector, when necessary, requires the removal or lifting of the top plate of the appliance or the removal of the front, with the result that the operation is never easy and convenient.

These known burners are also rather rigid in their operating capabilities, in that they only ensure correct combustion for given pressure and gas flow conditions, a factor which means that such burners are not suited to every appliance and therefore makes it necessary to have a range of different burners to suit all requirements.

The object of this invention is to produce a gas burner for cookers and hobs which comprises units which can be combined with ease, are conveniently accessible and are easily separable so as to eliminate the inconveniences and disadvantages of existing burners.

Another object of the invention is to seek to provide a burner including units shaped so as to produce the so-called venturi effect in mixing and distribution of the gas, the said effect being obtained substantially between the support of the flame spreader and the flame spreader itself, in a radial direction and over a circular course from the centre towards the holes of the said flame spreader unit. This provides the burner with considerable versatility and flexibility in use in that correct and complete combustion is maintained at all times even in the case of extensive gas pressure variations and with all types of gas. The burner is therefore suitable for all operating requirements and can be fitted to any cooker or hob.

A further object of the invention is to seek to provide a gas burner of very low height which can therefore be used with advantage in hobs which must be flat or, in any event, as low as possible compatible with the installation requirements of the hob itself.

Yet another object of the invention is to seek to provide a burner in which the primary air for mixing is drawn from the exterior directly above the cooker top or hob, eliminating the provision of a closed and isolated box or air intakes below the said level as happens when traditional gas burners are used.

Yet another object of the invention is to seek to provide a gas burner which is easier to locate and centre and is stable when placed directly on the top of a cooker or hob, the said burner also being capable of being fitted with a flame spreader of the conventional type, which is therefore easily available."


There are 7 claims, but it is common ground that it is sufficient to look at the first claim. The amended claim 1 is in the following form (as divided by the judge into numbered paragraphs):

"A burner for gas cookers and hobs, comprising

(i) a support bearing a gas supply injector or needle,

(ii) a body associated with this support defining a chamber in which the gas is mixed with primary air drawn from the outside, and

(iii) a flame spreader unit mounted on the said body defining therewith a passage for promoting complete mixing of the gas and primary air and for the supply of the gas-air mixture for burning through the holes of the said flame spreader,

(iv) wherein the said support has a sleeve portion having a...

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