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The centenary patent – Single-sleeve valve engines
World Patent Information 32 (2010) 320–325
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The centenary patent – Single-sleeve valve engines S.R. Adams Magister Ltd., Crown House, 231 Kings Road, Reading, RG1 4LS, UK
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Keywords: Historical Centenary Internal combustion engines Single-sleeve valve Burt–McCollum Car engine Automobile engine Aero engine Litigation
a b s t r a c t This article commemorates the centenary of the grant of a key patent in the development of the singlesleeve valve (often referred to as the Burt–McCollum sleeve valve). This emerged as an alternative to the conventional spring-loaded poppet-valve systems in internal combustion engines in automobiles, especially in applications where their smoother and quieter characteristics are significant. The rivalry and litigation resulting from several inventors patenting similar systems at about the same time is described, together with the later application of the single-sleeve valve system to aero engines. Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction The year 2010 sees the centenary of a British patent protecting a significant development in the design of internal combustion engines. The patent, No. 18,140 of 1909 [1] was granted to Argylls Limited of Alexandria, in Dumbartonshire, Scotland, on 8th August 1910. The inventor, Peter Burt,1 disclosed ‘‘An improved internal combustion engine”, in which the main feature was a re-designed valve arrangement delivering smoother running and substantial noise reduction. The design is widely referred to today in engineering circles as the ‘‘Burt–McCollum” sleeve valve; the reason for the double attribution will become evident later in this paper. It is appropriate at this point to acknowledge two major sources of information used in the preparation of this article. Refs. [2] and [3] are both PDF copies of original typed manuscripts, loaded on the website www.argyllmotors.co.uk, which is an unofficial history of Argylls, the Scottish firm which developed the Burt designs. Ref. [2] was written by Archie McPhail Niven, the great-uncle of the website owner Mr. Ken McEwen. Mr. Niven worked for Argylls and later for Continental Motors in Detroit, who acquired the Burt patents. Further background information on the company was obtained from a second website, Ref. [4]. 2. The ‘long-felt need’ and technical development Generations of engineers have grown up learning about the 4-stroke cycle of the common petrol-driven engine, colloquially E-mail address: [email protected] For aficionados of data quality, it is worth noting that Peter Burt was a Glasgow magistrate as well as an engineer, and his honorary legal title of ‘‘Baillie” has become confused in some internet resources as if it was his first given name – a mistake which a cursory examination of the patent front page resolves. 1
0172-2190/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.wpi.2010.05.005
known as the suck-squeeze-bang-blow cycle. At two points during a complete cycle, it is necessary for each cylinder to have open access for gas flows. During the inlet phase, fresh fuel–air mixture is admitted to the cylinder headspace (suck) above the piston. The cylinder is then sealed, the mixture is compressed (squeeze) and ignited by a sparking plug (bang), which forces the piston downwards on the power stroke. During the exhaust phase, the cylinder must be re-opened to permit the burnt gases to be expelled (blow), prior to the next inlet phase. An efficient 4-stroke engine therefore has to manage a delicate balance of factors; the inlet and exhaust vents must be perfectly gas-tight during the compression and ignition phases, but must be able to transition rapidly to the open position for the exhaust and inlet phases. In the majority of modern engines, the two vents are sealed by spring-loaded poppet valves mounted at the top of the cylinder head. In the early days of 4-stroke engines, many problems were caused by failure of the valve spring or excessive wear of the poppet valve, particularly the seating. These failures would doubtless have stimulated engineers to consider different valve arrangements, in parallel with the continued development of poppet-valve technology which, over many years, has substantially eliminated these earlier problems. The Argylls patent of 1910 presented an entirely different manner of achieving the required valve integrity and timing. The inlet and exhaust vents of the cylinder are bored through the sides of the cylinder head, instead of at the top. A loose liner, or sleeve, is mounted coaxially with the piston head, between the inside wall of the cylinder and the piston itself and occupying the full length of the cylinder. The sleeve is pierced at several points with shaped holes, or ports. The sleeve is able to move in two axes; a reciprocating motion parallel to the piston, and a partial rotation around the inner circumference of the cylinder head. These two motions are controlled via the crankshaft, and are
S.R. Adams / World Patent Information 32 (2010) 320–325
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designed such that during the inlet phase, the inlet vents in the side of the cylinder line up with the corresponding inlet ports on the sleeve, thus allowing the fuel–air mixture to enter the cylinder headspace. For the compression and ignition phases, the sleeve moves to a position in which none of the sleeve ports align with the vents, effectively sealing the cylinder. For exhaust, the sleeve rotates to bring a second set of ports into alignment with the exhaust vents of the cylinder, to enable the waste gas to be expelled. An overall view can be seen in Fig. 1. The piston head (d) is shown surrounded by the sleeve (g) which lies between the piston and the inner circumference of the cylinder (a). A single port (h) is shown in the wall of the sleeve, to the right of the sparking plug, and two vents (b, b0 ) in the wall of the cylinder can be seen either side of the headspace above the piston. The motion of the sleeve is controlled through its connection via pin (j) to a gearing arrangement (k0 ), (s) and (t) which ultimately link to the crankshaft (l). Although it appears more complex than a poppet-valve system, there are certain advantages to sleeve valves. One of these is the higher compression ratio which the fully-developed system can withstand, and was to make it possible for a logical development of the Burt system into aero engines. Another is the fact that, unlike poppet valves, the engine power needed to operate the sleeve valve remains relatively constant, even at higher revolutions-per-minute. In early engines, the return springs used to operate poppet valves could suffer from so-called ‘valve float’ at high engine speeds, resulting in the valve not closing quickly enough and striking the top of the rising piston. Modern poppetvalve systems used in Formula 1 cars can operate at up to 18,000 rpm without suffering this problem, but sleeve valves have been considered even for this type of application [5]. A third advantage of the Burt design was the elimination of the overhead camshaft and all the pushrods and valve rockers, since all the sleeve valves can be operated by a single gear from the crankshaft.
Fig. 1 is taken from US 1310646, the US equivalent to GB 18140/ 1909, and having rather clearer drawings than its parent. An alternative general-arrangement drawing is shown in Fig. 2 [from The Autocar Handbook, p. 39, Fig. 24, London: Iliffe & Sons, c.1919, 9th ed.].
Fig. 1. Overall view of single-sleeve arrangement.
Fig. 2. General-arrangement view of Argyll valve system.
3. Parallel developments; securing the intellectual property Although it was certainly a novel single-sleeve design, the Burt patent was not the first attempt to use sleeve valves for internal combustion engines. A Chicago-based publisher and keen motorist, Charles Yale Knight, patented a system using two concentric sleeves earlier in the same decade, but it was mechanically not as robust as the Burt design, and suffered from high oil consumption. Nonetheless, it achieved Knight’s principal aim of offering substantially reduced engine noise for use in luxury cars, and the so-called ‘‘Silent Knight” engine was exhibited at the Chicago Auto Show in 1906. Knight’s first UK patent on the double-sleeve system appears to be GB 12355/1908 [6] although he is named as coinventor on an earlier case, GB 14729/1905 [7]. This earlier patent was to be the cause of considerable problems for Argylls later on. Knight attempted to get wider acceptance for his car engines by travelling to Europe, and indeed his later patent applications show that at some point between June 1908 and September 1909 he moved from Chicago to become resident in Coventry (the UK manufacturing base of the Daimler Company, and later a licensee of Knight’s 1908 patent). Other patents in Knight’s name were granted from 1910 onwards [8] which represented the beginning of a series on various aspects of motoring, and his profession changes from ‘publisher’ to ‘engineer’. Various car manufacturers, including Daimler, Voisin and Mercedes, licensed Knight’s engines over this period. According to the available records [2–4], Peter Burt appears to have met Col. J.S. Matthew [sic – not Matthews], the managing director of Argylls Ltd., in August 1909, within months of the incorporation of the company in January of that year. Matthew was sufficiently impressed to agree to undertake development in collaboration with Burt. The provisional patent application was filed on 6th August 1909, which may even have been before Burt and Matthew met – certainly it would have been a prudent step for a lone inventor before entering development talks. The complete specification was lodged the following February and the application was accepted on 8th August 1910 (see Table 1, column 1). There are references in historical material which suggest that family equivalents to GB 18140/1909 were filed, but the only one which has been traced with certainty is US 1310646-A.
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Table 1 Chart of competing patent applications around the Burt engine.
Applicant
1 Burt/Argylls
Patent No.
GB 18140/1909
June 1909 July 1909 August 1909 November 1909 December 1909 January 1910 February 1910 April 1910 May 1910 June 1910 August 1910 October 1910 November 1910 April 1911 October 1911
2 McCollum
3 McCollum
4 Cameron/Coats
5 Cameron/Coats
6 Hoiland
GB 14629/1909
GB 27327/1909
GB 16289/1909
GB 26947/1909
GB 9257/1910
22nd – Complete 13th – Complete 6th – Provisional 24th – Provisional
20th – Provisional 16th – Accepted
14th – Complete 2nd – Complete 16th – Complete 19th – Complete 16th – Accepted
30th – Accepted
8th – Accepted 20th – Accepted 3rd – Accepted 10th – Amended
This was filed within the Convention year on 3rd August 1910, but for some reason became an archetypal ‘submarine patent’, not emerging from prosecution until nearly 9 years later on 22nd July 1919, with a full 17-year term until July 1936. The US patent describes a slightly different means of obtaining the sleeve movement within the cylinder, compared to the British parent, and it is possible that this case would today be characterised as a continuation-in-part, although there is no evidence of this on the front page. However, as any experienced patent applicant will know, the priority filing may only be the beginning of a series of nasty surprises and consequent amendments. At some point during late 1909 or early 1910, Argylls were alerted to the existence of at least one patent filed by James McCollum, a Canadian national resident in Toronto. McCollum’s first case (Table 1, column 2) had been filed on 22nd June 1909, some 6 weeks before Burt’s provisional application. A related patent application by McCollum (column 3) was not filed until November 1909 and presented less of a difficulty, but his first case disclosed the same basic principle of a singlesleeve valve as the Burt application. However, in the Burt design, the sleeve is an open-ended cylinder which fits between the piston and the cylinder wall and controlled from inside the crankcase, from the base of the cylinders. The McCollum system also used a single sleeve, but mounted outside of the cylinder, instead of between the piston and the cylinder wall, and operated from above using a conventional pushrod and rocker system. This meant that the McCollum engine would be expected to exhibit all the rattle and noise which had inspired Knight in 1905 to try to develop a replacement [9]. When Argylls first made contact with McCollum, he was en route from Canada to negotiate licences on his engine with the French manufacturer Delaunay-Belleville, so he could have been a serious competitive threat if they had launched a car first. Col. Matthew eventually agreed terms with McCollum during 1910, and GB 18140/1909 was duly reprinted following a decision of the Comptroller-General on 10th April 1911. The reprint acknowledges the existence of GB 14629/1909 and disclaims the arrangement which this patent described.2 However, this was not the end of Argylls’ troubles. During prosecution, the Patent Office apparently identified a further patent with an earlier priority date than Burt’s, which had been filed by two individuals (identified by a manuscript addendum in Ref. [3] as Cameron and Coats), one of whom was a former engineer and the other a cur-
2 Niven’s article (Ref. [2], p. 3) claims that McCollum assigned his rights to Argylls, but since this would have taken place after the printing of GB 14629/1909, and we have no post-grant assignment records available, it is difficult to confirm this.
28th – Amended
rent draughtsman on Argylls’ own staff. There was a dispute as to whether their filing had involved improper use of information received in confidence, or was an independent invention, and the Patent Office launched an enquiry into whether Cameron and Coats had obtained a patent by improper means. The most likely candidate for this earlier patent is GB 16289/1909 [10] which was filed on 13th July 1909, a mere 3 weeks before Burt’s (Table 1, column 4). Although Cutbush (Ref. [3], p. 40) indicates that the Cameron-Coats patent was ‘amended to make reference to the Burt patent’, the available facsimile for this document only shows that it was amended under s.8 of the 1907 Act3 and unlike the McCollum case, there is no explicit reference to the Burt case within the text. Cameron and Coats clearly continued working in the field, as they are named patentees on a number of later cases relating to sleeve valves, including GB 26947/1909 [11] filed on 20th November 1909, again prior to the acceptance of the Burt patent (Table 1, column 5). By the time of the grant of the Burt patent in August 1910, Col. Matthew might have been forgiven for thinking that Peter Burt’s invention had caused Argylls quite enough legal, as well as technical, problems. But obtaining a patent right is only part of the struggle, and from here on the company began to try to commercialise the invention, by securing licence agreements with car manufacturers to use their engine. One of their first shocks came in discussions with the United States. It transpired that US manufacturers were already in negotiations with a rival New Zealand-based inventor, Edvard Hoiland. As a consequence, they were unwilling to consider using the Argyll engine until its patent status was established. By a circuitous route, Col. Matthew was able to contact Hoiland, who had been granted a United Kingdom patent [12] based on a later filing date than Burt’s, but for similar subject matter (Table 1, column 6). Hoiland settled for a relatively small fee of £200, his specification was amended to note Burt’s patent and the two McCollum patents, and the way appeared clear for Argylls to start to market the single-sleeve valve engine.
4. The Knight litigation As well as seeking licensees, the Burt design was used from around 1911 in the cars manufactured by Argylls themselves. Argylls Ltd. had been reformed at Alexandria, north-west of 3 Section 8(2) of the Patents and Designs Act 1907 relates to the powers of the Comptroller to require reference to other applications filed before, but published after, the case being examined. It is worth noting that under the 1907 Act, the Patent Office still had no powers to refuse the grant of a patent on the grounds of prior art being discovered, but only to require each patentee to acknowledge the existence of related art.
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Glasgow, from a former company, Argyll Motors Ltd., which had gone into liquidation. By 1914, their entire range of cars used sleeve-valve engines of Burt design. In 1909, the same year as the filing of the first Burt patent, the Daimler Company of Coventry had launched a car with an engine using the Knight double-sleeve valve system, patented from mid1908 [6]. When Charles Knight visited the British Motor Show organised by the Society of Motor Manufacturers and Traders at London’s Olympia exhibition halls in 1911, he saw a Piccard-Pictet vehicle featuring a licence-built Burt engine; the Swiss company had become an early licensee of Argylls. Knight and his financial backer, the Chicago entrepreneur Lyman Kilbourne, initially filed suit for patent infringement against Piccard’s UK agents, basing their case not on their double-sleeve design licensed to Daimler but their earlier 1905 case [7]. Argylls indemnified all their licensees against legal action, and writs were filed against Argylls in November 1911. Knight appears to have been in a particularly litigious mood at the time. In March of 1912, he had fought but lost a case in the French courts in relation to the same technology, although Cutbush’s account [3] suggests that this case was complicated by French requirements for compulsory working and was not solely concerned with infringement. Following this defeat, Knight issued a public warning in the British press in defence of his patents, and the case against Argylls proceeded to court. The hearing opened at the High Court, Chancery Division on 3rd July 1912. Argylls were clearly keen to mount a rigorous defence, since one of the two senior counsel representing them could without exaggeration be described as ‘the man who wrote the book on the subject’. It was Mr. Thomas Terrell, KC (1852–1928), who was the original author in 1884 of ‘‘The law and practice relating to letters patent for inventions”, soon to become the standard British text now known as ‘‘Terrell on Patents”.4 The patent in suit was cited as GB 14729* [sic] of 1905, in which the asterisk served as the equivalent to a modern Kindof-Document code and indicated that the patent had been amended by a decision of the Chief Examiner at the Patent Office. Argylls were able to prove that Knight’s patent was unworkable, partly by constructing an engine to his design and running experiments. The court felt that the specification as granted described two alternative ways of putting the invention into effect and that the amendment had effectively widened the scope of the claims, to give undue emphasis to the features in common with the Burt design. The judge in the case, Mr. Justice Neville, is reported in The Times Law Reports section [13] as saying that ‘‘the action was a somewhat audacious attempt to resuscitate a patent for an invention of small compass and. . .of very moderate utility, and by the help of an amendment to make it cover and embrace a wide field of enterprise. . .”. The action was dismissed and costs awarded against the plaintiffs [14]. The digitised facsimile of The Times law report on the case reveals a peculiar irony; nestling in the bottom right-hand corner of the same page, at column F, is an advertisement for Panhard cars (Fig. 3) powered by the 25 h.p. ‘‘Silent Knight” engine, the successful double-sleeve design patented by Knight in GB190812355. 4 In 1921, 8 years after the appeal, Sweet & Maxwell published the sixth edition of Thomas Terrell’s magnum opus, which was updated by his son Courtney Terrell and Arthur Jaffé. The previous edition had been some 12 years before, so the 1921 edition would have been the first opportunity to include reference to his father’s experiences in Knight-v-Argylls. The case is duly listed as a footnote on p. 110 in Chapter 6, ‘The Specification’, under the sub-heading ‘‘Sufficiency – the effect of errors.”
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Fig. 3. Advertisement from The Times, 26th July 1912, p. 3.
Despite their setback, Knight and Kilbourne appealed and the case was heard at the Court of Appeal the following year [15], before no less than Herbert Cozens-Hardy MR5 in panel with Buckley LJ and Hamilton LJ. The appeal court upheld the judgement of the lower court, that Argylls had not infringed. Although finally exonerated, their defence had cost the Scottish company a considerable amount of money and time. In the short term, the result increased confidence in the Argylls technology, and their share price rose by some 13% in the week of the appeal verdict, from 5/6d. to 6/3d. (approximately £0.27 to £0.31 in modern currency). 5. Argylls liquidation and the future of the IP Sadly, Argylls victory in court did not secure their long-term future. The single-sleeve valve engine was clearly a technical success, as shown by the motor racing trials at the famous Brooklands track in Surrey during May 1913, in which a car powered by a 2.6 litre Burt–McCollum engine maintained an average speed of over 72 m.p.h. (115 km/h) in a timed race over 14 h. Similarly, as war loomed in 1914, Argylls entered the official Aeroplane Engine competitions with a sleeve-valve design for an aero engine, and were offered a contract despite some mechanical failures. But the extended struggle to secure and defend their patent rights had exhausted the company’s resources, and Argylls was forced into receivership in June 1914. At this point, the ownership in their respective patents reverted to Peter Burt and James McCollum. Argyll’s place in Scottish motoring history is described in detail at the Motoring Heritage website [4], and it is clear that the winding-up was not without acrimony. Talks to allow a takeover by the Darracq motor company (which had been British-owned since 1913) failed. Arguments over patent rights continued even after the winding-up. McCollum claimed that he had some rights in several improvement patents which Argylls had filed between 1910 and 1914 [16] but the Court of Session sitting in Edinburgh disagreed. Little was done with the patents during the period of the First World War, although Burt’s GB 18140/1909 and McCollum’s GB 14629/1909 both benefited from a 4-year term extension by Court Order, probably under the post-war settlement on patent terms affected by war use [17]. All the Burt, McCollum and other Argylls patents, together with a package of related intellectual property from other patentees, were bought by Wallace (Glasgow) Ltd. in 1920, by which time the Burt and McCollum patents had only 5 years of life left (the term extensions were not granted until 1925, the original year of expiry). Although Wallace tried to market a range of car and boat engines using the technology, they did not succeed and the patents were again sold in 1925, this time to 5 The Master of the Rolls (entitled MR in legal citations) is the senior judge and presiding officer in the civil division of the Court of Appeal of England and Wales. The other judges of the court are entitled ‘Lord Justice’ (LJ).
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and Vickers Wellington. Fig. 4 is a photograph supplied by Wikimedia Commons of a Bristol Hercules engine exhibited at the Museum of Flight, East Fortune, Scotland. It is interesting to note in passing that Vickers by this time was employing the famous engineer Barnes Wallis, who had designed the Wellington. Wallis had himself experimented with, and patented, sleeve-valve engines during the late 1920s, whilst leading the design team at the Airship Guarantee Company (builders of the R.100 airship, sister to the ill-fated R.101) [19]. During the course of the late 1920s and into the 1940s, Fedden and the Bristol Aeroplane Company filed a string of patents on single-sleeve valve systems [20], and many of these documents acknowledge the seminal influence of the original Burt patent of 1910, usually referred to as ‘‘Burt–McCollum”. Even very recent patents emanating from Lotus continue to pay tribute to their work [5]. 7. Conclusion Fig. 4. Bristol Hercules engine, Museum of Flight. Wikimedia Commons, 2007.
Continental Motors of Detroit.6 Archie Niven had joined Continental Motors to help with development, and his paper [2] delivered in New York in 1926 notes the anticipation of ‘‘intensive production” of Burt–McCollum engines in the United States. The main area of interest appears to have been for aero engines. Nonetheless, despite their expertise, neither Continental nor Pratt & Witney, using competing sleeve-valve technology, succeeded in developing a workable engine for use in aircraft in the US. It was left to the Bristol Aeroplane Company, back in the United Kingdom, to produce the next chapter in the history of Burt–McCollum engines. 6. The move into the air As noted above, Argylls had experimented successfully with the development of a Burt–McCollum design engine for use in aircraft as early as 1914. However, it was not until the mid-1920s that serious consideration was given to this type of power unit. According to Niven (Ref. [2], pp. 18–19), an influential report by the British Aeronautical Committee in 1925–26 had noted that their Engine Sub-committee ‘‘are of the opinion that these engines offer definite advantages for use in aircraft.” A supplement to this report indicated that long-term running trials had been in place for at least a year before this, involving Harry (later Sir Harry) Ricardo (1885– 1974), a prominent engineer who had worked for the Royal Aircraft Establishment before founding Ricardo & Co., consulting engineers [18]. It is Ricardo who is credited with persuading A.H.R. Fedden (1885–1973, later Sir Roy Fedden, chief engineer at the Bristol Aeroplane Company) to try to develop a practical aircraft powerplant. Fedden had joined Bristol’s from the Cosmos Engineering company when it had been taken over in 1920, bringing his design team and the company’s patents with them. The first complete Bristol engine using sleeve-valve technology was the Bristol Perseus in 1932, which was used for the Short Scylla airliner operated by Imperial Airways (later British Airways). The family of engines grew with the development of the Bristol Aquila (1934) and the Taurus (1940), and culminated in the 14-cylinder two-row radial known as the Bristol Hercules. This powerplant was used in a wide range of aircraft, including the Short Stirling, Bristol Beaufighter (whose airframe was built by the Bristol Aeroplane Company, along with the engine), Handley-Page Halifax 6 Cutbush’s account (Ref. [3]) notes that other assets also crossed the Atlantic. A silver model of the Burt valve engine had been presented to H.R.H. Princess Louise, sister of King Edward VII, during her visit to the Argylls factory in 1913, and by 1927 this was in the possession of Continental Motors. It is interesting to speculate where it might be today.
The history of technology is littered with questions as to why apparently superior technology failed to capture the market; perhaps the classic case is the VHS-v-Betamax struggles over videotaping. Knight recognised that sleeve valves could deliver his desired ‘unique selling point’ (reduction in engine noise) but at a cost in mechanical efficiency. It was not for the want of trying that the technology failed on land. It is possible to argue that Argylls’ collapse so shortly after their success in the Knight litigation, and the subsequent events of the First World War, contributed to the relative lack of success in developing these types of engine. In the air, many British aircraft of the early war period were powered by a third engine type, the rotary, which was initially built by French manufacturers such as Gnome, Le Rhône and Clerget or their British licence-holders. Perhaps it was felt that developing too many different types of engine (rotary, in-line poppet-valve and sleeve-valve) would place an unacceptable training burden on an already stretched corps of mechanics, and reduce the effectiveness of the war effort. After the war, the efforts of Wallace (Glasgow) Ltd. in the 1920s still failed to provide the breakthrough on land or water, and by this time poppet valves had developed sufficiently to gain a stranglehold on car engine applications. There is no doubt that Archie Niven’s presentation in 1926 anticipated that aero engines could be the future niche for sleeve-valve technology, but US companies failed to capitalise on this. Eventually, British success in the shape of the Bristol series led to an engine which, by all accounts, ran like the proverbial sewing machine
Fig. 5. Bristol Type 170 Freighter, RAAF Museum, Point Cook, Melbourne. Photograph Ó S. Adams, 2008, used with permission.
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and could have had an enormous impact on land vehicle powerplants if adopted, but by that time it was too late. The car industry has apparently concentrated more effort on advanced diesel technology, and even innovations like the rotary Wankel engine have had little success [21]. I would like to conclude this article with mention of a personal link. As well as its use in famous wartime aircraft, the fully-developed Bristol Hercules model 734 engine, which produced 1980 h.p., was fitted to a much later Bristol-built aircraft, the Type 170 Freighter (Fig. 5). This was operated by Silver City Airways from Lydd Airport in Kent on the cross-Channel car ferry route to Le Touquet in northern France. My father was an engineer with Silver City when I was born in Lydd, and thus it is quite likely that the first aero engine I ever heard was a Bristol Hercules developed using Burt–McCollum technology. It was certainly the first aircraft in which I flew as a passenger, in 1964. At the height of the summer season, operations ran from 07:30 to 23:00 each day and Silver City aircraft would fly multiple return trips between Lydd and Le Touquet, each sector of some 20 min flying time. The distinctive note of their Bristol Hercules engines was the backdrop to my earliest aviation experiences. References [1] Burt P, Argylls Limited. GB 190918140-A, accepted 8th August 1910. [2] Niven AM. The single-sleeve valve engine. Paper given at the meeting of the Metropolitan Section (New York) of the Society of Automotive Engineers; 15th November 1926. Partial facsimile copy. Available from: [accessed 26.02.10]. [3] Cutbush GH. The story of the single-sleeve valve engine; 1927. Facsimile copy. Available from: [accessed 26.02.10]. [4] [accessed 27.02.10]. [5] Lotus Cars Ltd., GB 2432398-B, granted 13th August 2008. [6] Knight CY. GB 190812355-A, accepted 3rd June 1909. [7] Knight CY, Kilbourne LB. GB 190514729-A, accepted 14th September 1905. [8] Knight CY. GB 190921645-A, accepted 22nd September 1910; Knight CY. GB 191009280-A, accepted 13th April 1911, and others.
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[9] Technical explanation derived from information provided at: http:// www.enginehistory.org/pioneering_sleeve_valve.htm [accessed 26.02.10]. [10] Cameron W, Coats A. GB 190916289-A, accepted 16th December 1909. [11] Cameron W, Coats A. GB 190926947-A, accepted 20th October 1910. [12] Hoiland E. GB 191009257-A, accepted 3rd November 1910. [13] The Times, Friday 26th July, 1912, issue 39961, p. 3, column B. [14] Knight-v-Argylls (Limited). (1912) 29 RPC 593, High Court, Chancery. [15] Knight-v-Argylls (Limited). (1913) 30 RPC 321, Court of Appeal. [16] Probably including, Burt P. Argylls Ltd. GB 191025438-A, accepted 3rd August 1911; Burt P, Matthew JS. Argylls Ltd. GB 191305683-A, accepted 20th November 1913; Burt P, Matthew JS. Argylls Ltd. GB 191307879-A, accepted 12th February 1914. [17] See the PDF copies of the original documents for addendum page, and van Dulken S. British Patents of Invention 1617–1977: a guide for researchers, p. 43–45, Section 2.21 (Extension of the patent term). London: British Library Board; 1999. ISBN 0-7123-0817-2. [18]
S.R. Adams is founder and managing director of Magister Ltd., an information and training consultancy specialising in patents documentation. He trained as a chemist at the University of Bristol, UK, followed by a Masters degree in Information Science at City University, London. He has worked in technical information since 1981, latterly with Zeneca Agrochemicals (now Syngenta) as their principal patent searcher until 1997. He has also been the editor of ‘‘International Packaging Abstracts’’, a technical searcher in the Ministry of Agriculture, Fisheries & Food in the UK, and Chair of the Patent and Trade Mark Group.
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The centenary patent – Single-sleeve valve engines S.R. Adams Magister Ltd., Crown House, 231 Kings Road, Reading, RG1 4LS, UK
a r t i c l e
i n f o
Keywords: Historical Centenary Internal combustion engines Single-sleeve valve Burt–McCollum Car engine Automobile engine Aero engine Litigation
a b s t r a c t This article commemorates the centenary of the grant of a key patent in the development of the singlesleeve valve (often referred to as the Burt–McCollum sleeve valve). This emerged as an alternative to the conventional spring-loaded poppet-valve systems in internal combustion engines in automobiles, especially in applications where their smoother and quieter characteristics are significant. The rivalry and litigation resulting from several inventors patenting similar systems at about the same time is described, together with the later application of the single-sleeve valve system to aero engines. Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction The year 2010 sees the centenary of a British patent protecting a significant development in the design of internal combustion engines. The patent, No. 18,140 of 1909 [1] was granted to Argylls Limited of Alexandria, in Dumbartonshire, Scotland, on 8th August 1910. The inventor, Peter Burt,1 disclosed ‘‘An improved internal combustion engine”, in which the main feature was a re-designed valve arrangement delivering smoother running and substantial noise reduction. The design is widely referred to today in engineering circles as the ‘‘Burt–McCollum” sleeve valve; the reason for the double attribution will become evident later in this paper. It is appropriate at this point to acknowledge two major sources of information used in the preparation of this article. Refs. [2] and [3] are both PDF copies of original typed manuscripts, loaded on the website www.argyllmotors.co.uk, which is an unofficial history of Argylls, the Scottish firm which developed the Burt designs. Ref. [2] was written by Archie McPhail Niven, the great-uncle of the website owner Mr. Ken McEwen. Mr. Niven worked for Argylls and later for Continental Motors in Detroit, who acquired the Burt patents. Further background information on the company was obtained from a second website, Ref. [4]. 2. The ‘long-felt need’ and technical development Generations of engineers have grown up learning about the 4-stroke cycle of the common petrol-driven engine, colloquially E-mail address: [email protected] For aficionados of data quality, it is worth noting that Peter Burt was a Glasgow magistrate as well as an engineer, and his honorary legal title of ‘‘Baillie” has become confused in some internet resources as if it was his first given name – a mistake which a cursory examination of the patent front page resolves. 1
0172-2190/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.wpi.2010.05.005
known as the suck-squeeze-bang-blow cycle. At two points during a complete cycle, it is necessary for each cylinder to have open access for gas flows. During the inlet phase, fresh fuel–air mixture is admitted to the cylinder headspace (suck) above the piston. The cylinder is then sealed, the mixture is compressed (squeeze) and ignited by a sparking plug (bang), which forces the piston downwards on the power stroke. During the exhaust phase, the cylinder must be re-opened to permit the burnt gases to be expelled (blow), prior to the next inlet phase. An efficient 4-stroke engine therefore has to manage a delicate balance of factors; the inlet and exhaust vents must be perfectly gas-tight during the compression and ignition phases, but must be able to transition rapidly to the open position for the exhaust and inlet phases. In the majority of modern engines, the two vents are sealed by spring-loaded poppet valves mounted at the top of the cylinder head. In the early days of 4-stroke engines, many problems were caused by failure of the valve spring or excessive wear of the poppet valve, particularly the seating. These failures would doubtless have stimulated engineers to consider different valve arrangements, in parallel with the continued development of poppet-valve technology which, over many years, has substantially eliminated these earlier problems. The Argylls patent of 1910 presented an entirely different manner of achieving the required valve integrity and timing. The inlet and exhaust vents of the cylinder are bored through the sides of the cylinder head, instead of at the top. A loose liner, or sleeve, is mounted coaxially with the piston head, between the inside wall of the cylinder and the piston itself and occupying the full length of the cylinder. The sleeve is pierced at several points with shaped holes, or ports. The sleeve is able to move in two axes; a reciprocating motion parallel to the piston, and a partial rotation around the inner circumference of the cylinder head. These two motions are controlled via the crankshaft, and are
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designed such that during the inlet phase, the inlet vents in the side of the cylinder line up with the corresponding inlet ports on the sleeve, thus allowing the fuel–air mixture to enter the cylinder headspace. For the compression and ignition phases, the sleeve moves to a position in which none of the sleeve ports align with the vents, effectively sealing the cylinder. For exhaust, the sleeve rotates to bring a second set of ports into alignment with the exhaust vents of the cylinder, to enable the waste gas to be expelled. An overall view can be seen in Fig. 1. The piston head (d) is shown surrounded by the sleeve (g) which lies between the piston and the inner circumference of the cylinder (a). A single port (h) is shown in the wall of the sleeve, to the right of the sparking plug, and two vents (b, b0 ) in the wall of the cylinder can be seen either side of the headspace above the piston. The motion of the sleeve is controlled through its connection via pin (j) to a gearing arrangement (k0 ), (s) and (t) which ultimately link to the crankshaft (l). Although it appears more complex than a poppet-valve system, there are certain advantages to sleeve valves. One of these is the higher compression ratio which the fully-developed system can withstand, and was to make it possible for a logical development of the Burt system into aero engines. Another is the fact that, unlike poppet valves, the engine power needed to operate the sleeve valve remains relatively constant, even at higher revolutions-per-minute. In early engines, the return springs used to operate poppet valves could suffer from so-called ‘valve float’ at high engine speeds, resulting in the valve not closing quickly enough and striking the top of the rising piston. Modern poppetvalve systems used in Formula 1 cars can operate at up to 18,000 rpm without suffering this problem, but sleeve valves have been considered even for this type of application [5]. A third advantage of the Burt design was the elimination of the overhead camshaft and all the pushrods and valve rockers, since all the sleeve valves can be operated by a single gear from the crankshaft.
Fig. 1 is taken from US 1310646, the US equivalent to GB 18140/ 1909, and having rather clearer drawings than its parent. An alternative general-arrangement drawing is shown in Fig. 2 [from The Autocar Handbook, p. 39, Fig. 24, London: Iliffe & Sons, c.1919, 9th ed.].
Fig. 1. Overall view of single-sleeve arrangement.
Fig. 2. General-arrangement view of Argyll valve system.
3. Parallel developments; securing the intellectual property Although it was certainly a novel single-sleeve design, the Burt patent was not the first attempt to use sleeve valves for internal combustion engines. A Chicago-based publisher and keen motorist, Charles Yale Knight, patented a system using two concentric sleeves earlier in the same decade, but it was mechanically not as robust as the Burt design, and suffered from high oil consumption. Nonetheless, it achieved Knight’s principal aim of offering substantially reduced engine noise for use in luxury cars, and the so-called ‘‘Silent Knight” engine was exhibited at the Chicago Auto Show in 1906. Knight’s first UK patent on the double-sleeve system appears to be GB 12355/1908 [6] although he is named as coinventor on an earlier case, GB 14729/1905 [7]. This earlier patent was to be the cause of considerable problems for Argylls later on. Knight attempted to get wider acceptance for his car engines by travelling to Europe, and indeed his later patent applications show that at some point between June 1908 and September 1909 he moved from Chicago to become resident in Coventry (the UK manufacturing base of the Daimler Company, and later a licensee of Knight’s 1908 patent). Other patents in Knight’s name were granted from 1910 onwards [8] which represented the beginning of a series on various aspects of motoring, and his profession changes from ‘publisher’ to ‘engineer’. Various car manufacturers, including Daimler, Voisin and Mercedes, licensed Knight’s engines over this period. According to the available records [2–4], Peter Burt appears to have met Col. J.S. Matthew [sic – not Matthews], the managing director of Argylls Ltd., in August 1909, within months of the incorporation of the company in January of that year. Matthew was sufficiently impressed to agree to undertake development in collaboration with Burt. The provisional patent application was filed on 6th August 1909, which may even have been before Burt and Matthew met – certainly it would have been a prudent step for a lone inventor before entering development talks. The complete specification was lodged the following February and the application was accepted on 8th August 1910 (see Table 1, column 1). There are references in historical material which suggest that family equivalents to GB 18140/1909 were filed, but the only one which has been traced with certainty is US 1310646-A.
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Table 1 Chart of competing patent applications around the Burt engine.
Applicant
1 Burt/Argylls
Patent No.
GB 18140/1909
June 1909 July 1909 August 1909 November 1909 December 1909 January 1910 February 1910 April 1910 May 1910 June 1910 August 1910 October 1910 November 1910 April 1911 October 1911
2 McCollum
3 McCollum
4 Cameron/Coats
5 Cameron/Coats
6 Hoiland
GB 14629/1909
GB 27327/1909
GB 16289/1909
GB 26947/1909
GB 9257/1910
22nd – Complete 13th – Complete 6th – Provisional 24th – Provisional
20th – Provisional 16th – Accepted
14th – Complete 2nd – Complete 16th – Complete 19th – Complete 16th – Accepted
30th – Accepted
8th – Accepted 20th – Accepted 3rd – Accepted 10th – Amended
This was filed within the Convention year on 3rd August 1910, but for some reason became an archetypal ‘submarine patent’, not emerging from prosecution until nearly 9 years later on 22nd July 1919, with a full 17-year term until July 1936. The US patent describes a slightly different means of obtaining the sleeve movement within the cylinder, compared to the British parent, and it is possible that this case would today be characterised as a continuation-in-part, although there is no evidence of this on the front page. However, as any experienced patent applicant will know, the priority filing may only be the beginning of a series of nasty surprises and consequent amendments. At some point during late 1909 or early 1910, Argylls were alerted to the existence of at least one patent filed by James McCollum, a Canadian national resident in Toronto. McCollum’s first case (Table 1, column 2) had been filed on 22nd June 1909, some 6 weeks before Burt’s provisional application. A related patent application by McCollum (column 3) was not filed until November 1909 and presented less of a difficulty, but his first case disclosed the same basic principle of a singlesleeve valve as the Burt application. However, in the Burt design, the sleeve is an open-ended cylinder which fits between the piston and the cylinder wall and controlled from inside the crankcase, from the base of the cylinders. The McCollum system also used a single sleeve, but mounted outside of the cylinder, instead of between the piston and the cylinder wall, and operated from above using a conventional pushrod and rocker system. This meant that the McCollum engine would be expected to exhibit all the rattle and noise which had inspired Knight in 1905 to try to develop a replacement [9]. When Argylls first made contact with McCollum, he was en route from Canada to negotiate licences on his engine with the French manufacturer Delaunay-Belleville, so he could have been a serious competitive threat if they had launched a car first. Col. Matthew eventually agreed terms with McCollum during 1910, and GB 18140/1909 was duly reprinted following a decision of the Comptroller-General on 10th April 1911. The reprint acknowledges the existence of GB 14629/1909 and disclaims the arrangement which this patent described.2 However, this was not the end of Argylls’ troubles. During prosecution, the Patent Office apparently identified a further patent with an earlier priority date than Burt’s, which had been filed by two individuals (identified by a manuscript addendum in Ref. [3] as Cameron and Coats), one of whom was a former engineer and the other a cur-
2 Niven’s article (Ref. [2], p. 3) claims that McCollum assigned his rights to Argylls, but since this would have taken place after the printing of GB 14629/1909, and we have no post-grant assignment records available, it is difficult to confirm this.
28th – Amended
rent draughtsman on Argylls’ own staff. There was a dispute as to whether their filing had involved improper use of information received in confidence, or was an independent invention, and the Patent Office launched an enquiry into whether Cameron and Coats had obtained a patent by improper means. The most likely candidate for this earlier patent is GB 16289/1909 [10] which was filed on 13th July 1909, a mere 3 weeks before Burt’s (Table 1, column 4). Although Cutbush (Ref. [3], p. 40) indicates that the Cameron-Coats patent was ‘amended to make reference to the Burt patent’, the available facsimile for this document only shows that it was amended under s.8 of the 1907 Act3 and unlike the McCollum case, there is no explicit reference to the Burt case within the text. Cameron and Coats clearly continued working in the field, as they are named patentees on a number of later cases relating to sleeve valves, including GB 26947/1909 [11] filed on 20th November 1909, again prior to the acceptance of the Burt patent (Table 1, column 5). By the time of the grant of the Burt patent in August 1910, Col. Matthew might have been forgiven for thinking that Peter Burt’s invention had caused Argylls quite enough legal, as well as technical, problems. But obtaining a patent right is only part of the struggle, and from here on the company began to try to commercialise the invention, by securing licence agreements with car manufacturers to use their engine. One of their first shocks came in discussions with the United States. It transpired that US manufacturers were already in negotiations with a rival New Zealand-based inventor, Edvard Hoiland. As a consequence, they were unwilling to consider using the Argyll engine until its patent status was established. By a circuitous route, Col. Matthew was able to contact Hoiland, who had been granted a United Kingdom patent [12] based on a later filing date than Burt’s, but for similar subject matter (Table 1, column 6). Hoiland settled for a relatively small fee of £200, his specification was amended to note Burt’s patent and the two McCollum patents, and the way appeared clear for Argylls to start to market the single-sleeve valve engine.
4. The Knight litigation As well as seeking licensees, the Burt design was used from around 1911 in the cars manufactured by Argylls themselves. Argylls Ltd. had been reformed at Alexandria, north-west of 3 Section 8(2) of the Patents and Designs Act 1907 relates to the powers of the Comptroller to require reference to other applications filed before, but published after, the case being examined. It is worth noting that under the 1907 Act, the Patent Office still had no powers to refuse the grant of a patent on the grounds of prior art being discovered, but only to require each patentee to acknowledge the existence of related art.
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Glasgow, from a former company, Argyll Motors Ltd., which had gone into liquidation. By 1914, their entire range of cars used sleeve-valve engines of Burt design. In 1909, the same year as the filing of the first Burt patent, the Daimler Company of Coventry had launched a car with an engine using the Knight double-sleeve valve system, patented from mid1908 [6]. When Charles Knight visited the British Motor Show organised by the Society of Motor Manufacturers and Traders at London’s Olympia exhibition halls in 1911, he saw a Piccard-Pictet vehicle featuring a licence-built Burt engine; the Swiss company had become an early licensee of Argylls. Knight and his financial backer, the Chicago entrepreneur Lyman Kilbourne, initially filed suit for patent infringement against Piccard’s UK agents, basing their case not on their double-sleeve design licensed to Daimler but their earlier 1905 case [7]. Argylls indemnified all their licensees against legal action, and writs were filed against Argylls in November 1911. Knight appears to have been in a particularly litigious mood at the time. In March of 1912, he had fought but lost a case in the French courts in relation to the same technology, although Cutbush’s account [3] suggests that this case was complicated by French requirements for compulsory working and was not solely concerned with infringement. Following this defeat, Knight issued a public warning in the British press in defence of his patents, and the case against Argylls proceeded to court. The hearing opened at the High Court, Chancery Division on 3rd July 1912. Argylls were clearly keen to mount a rigorous defence, since one of the two senior counsel representing them could without exaggeration be described as ‘the man who wrote the book on the subject’. It was Mr. Thomas Terrell, KC (1852–1928), who was the original author in 1884 of ‘‘The law and practice relating to letters patent for inventions”, soon to become the standard British text now known as ‘‘Terrell on Patents”.4 The patent in suit was cited as GB 14729* [sic] of 1905, in which the asterisk served as the equivalent to a modern Kindof-Document code and indicated that the patent had been amended by a decision of the Chief Examiner at the Patent Office. Argylls were able to prove that Knight’s patent was unworkable, partly by constructing an engine to his design and running experiments. The court felt that the specification as granted described two alternative ways of putting the invention into effect and that the amendment had effectively widened the scope of the claims, to give undue emphasis to the features in common with the Burt design. The judge in the case, Mr. Justice Neville, is reported in The Times Law Reports section [13] as saying that ‘‘the action was a somewhat audacious attempt to resuscitate a patent for an invention of small compass and. . .of very moderate utility, and by the help of an amendment to make it cover and embrace a wide field of enterprise. . .”. The action was dismissed and costs awarded against the plaintiffs [14]. The digitised facsimile of The Times law report on the case reveals a peculiar irony; nestling in the bottom right-hand corner of the same page, at column F, is an advertisement for Panhard cars (Fig. 3) powered by the 25 h.p. ‘‘Silent Knight” engine, the successful double-sleeve design patented by Knight in GB190812355. 4 In 1921, 8 years after the appeal, Sweet & Maxwell published the sixth edition of Thomas Terrell’s magnum opus, which was updated by his son Courtney Terrell and Arthur Jaffé. The previous edition had been some 12 years before, so the 1921 edition would have been the first opportunity to include reference to his father’s experiences in Knight-v-Argylls. The case is duly listed as a footnote on p. 110 in Chapter 6, ‘The Specification’, under the sub-heading ‘‘Sufficiency – the effect of errors.”
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Fig. 3. Advertisement from The Times, 26th July 1912, p. 3.
Despite their setback, Knight and Kilbourne appealed and the case was heard at the Court of Appeal the following year [15], before no less than Herbert Cozens-Hardy MR5 in panel with Buckley LJ and Hamilton LJ. The appeal court upheld the judgement of the lower court, that Argylls had not infringed. Although finally exonerated, their defence had cost the Scottish company a considerable amount of money and time. In the short term, the result increased confidence in the Argylls technology, and their share price rose by some 13% in the week of the appeal verdict, from 5/6d. to 6/3d. (approximately £0.27 to £0.31 in modern currency). 5. Argylls liquidation and the future of the IP Sadly, Argylls victory in court did not secure their long-term future. The single-sleeve valve engine was clearly a technical success, as shown by the motor racing trials at the famous Brooklands track in Surrey during May 1913, in which a car powered by a 2.6 litre Burt–McCollum engine maintained an average speed of over 72 m.p.h. (115 km/h) in a timed race over 14 h. Similarly, as war loomed in 1914, Argylls entered the official Aeroplane Engine competitions with a sleeve-valve design for an aero engine, and were offered a contract despite some mechanical failures. But the extended struggle to secure and defend their patent rights had exhausted the company’s resources, and Argylls was forced into receivership in June 1914. At this point, the ownership in their respective patents reverted to Peter Burt and James McCollum. Argyll’s place in Scottish motoring history is described in detail at the Motoring Heritage website [4], and it is clear that the winding-up was not without acrimony. Talks to allow a takeover by the Darracq motor company (which had been British-owned since 1913) failed. Arguments over patent rights continued even after the winding-up. McCollum claimed that he had some rights in several improvement patents which Argylls had filed between 1910 and 1914 [16] but the Court of Session sitting in Edinburgh disagreed. Little was done with the patents during the period of the First World War, although Burt’s GB 18140/1909 and McCollum’s GB 14629/1909 both benefited from a 4-year term extension by Court Order, probably under the post-war settlement on patent terms affected by war use [17]. All the Burt, McCollum and other Argylls patents, together with a package of related intellectual property from other patentees, were bought by Wallace (Glasgow) Ltd. in 1920, by which time the Burt and McCollum patents had only 5 years of life left (the term extensions were not granted until 1925, the original year of expiry). Although Wallace tried to market a range of car and boat engines using the technology, they did not succeed and the patents were again sold in 1925, this time to 5 The Master of the Rolls (entitled MR in legal citations) is the senior judge and presiding officer in the civil division of the Court of Appeal of England and Wales. The other judges of the court are entitled ‘Lord Justice’ (LJ).
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and Vickers Wellington. Fig. 4 is a photograph supplied by Wikimedia Commons of a Bristol Hercules engine exhibited at the Museum of Flight, East Fortune, Scotland. It is interesting to note in passing that Vickers by this time was employing the famous engineer Barnes Wallis, who had designed the Wellington. Wallis had himself experimented with, and patented, sleeve-valve engines during the late 1920s, whilst leading the design team at the Airship Guarantee Company (builders of the R.100 airship, sister to the ill-fated R.101) [19]. During the course of the late 1920s and into the 1940s, Fedden and the Bristol Aeroplane Company filed a string of patents on single-sleeve valve systems [20], and many of these documents acknowledge the seminal influence of the original Burt patent of 1910, usually referred to as ‘‘Burt–McCollum”. Even very recent patents emanating from Lotus continue to pay tribute to their work [5]. 7. Conclusion Fig. 4. Bristol Hercules engine, Museum of Flight. Wikimedia Commons, 2007.
Continental Motors of Detroit.6 Archie Niven had joined Continental Motors to help with development, and his paper [2] delivered in New York in 1926 notes the anticipation of ‘‘intensive production” of Burt–McCollum engines in the United States. The main area of interest appears to have been for aero engines. Nonetheless, despite their expertise, neither Continental nor Pratt & Witney, using competing sleeve-valve technology, succeeded in developing a workable engine for use in aircraft in the US. It was left to the Bristol Aeroplane Company, back in the United Kingdom, to produce the next chapter in the history of Burt–McCollum engines. 6. The move into the air As noted above, Argylls had experimented successfully with the development of a Burt–McCollum design engine for use in aircraft as early as 1914. However, it was not until the mid-1920s that serious consideration was given to this type of power unit. According to Niven (Ref. [2], pp. 18–19), an influential report by the British Aeronautical Committee in 1925–26 had noted that their Engine Sub-committee ‘‘are of the opinion that these engines offer definite advantages for use in aircraft.” A supplement to this report indicated that long-term running trials had been in place for at least a year before this, involving Harry (later Sir Harry) Ricardo (1885– 1974), a prominent engineer who had worked for the Royal Aircraft Establishment before founding Ricardo & Co., consulting engineers [18]. It is Ricardo who is credited with persuading A.H.R. Fedden (1885–1973, later Sir Roy Fedden, chief engineer at the Bristol Aeroplane Company) to try to develop a practical aircraft powerplant. Fedden had joined Bristol’s from the Cosmos Engineering company when it had been taken over in 1920, bringing his design team and the company’s patents with them. The first complete Bristol engine using sleeve-valve technology was the Bristol Perseus in 1932, which was used for the Short Scylla airliner operated by Imperial Airways (later British Airways). The family of engines grew with the development of the Bristol Aquila (1934) and the Taurus (1940), and culminated in the 14-cylinder two-row radial known as the Bristol Hercules. This powerplant was used in a wide range of aircraft, including the Short Stirling, Bristol Beaufighter (whose airframe was built by the Bristol Aeroplane Company, along with the engine), Handley-Page Halifax 6 Cutbush’s account (Ref. [3]) notes that other assets also crossed the Atlantic. A silver model of the Burt valve engine had been presented to H.R.H. Princess Louise, sister of King Edward VII, during her visit to the Argylls factory in 1913, and by 1927 this was in the possession of Continental Motors. It is interesting to speculate where it might be today.
The history of technology is littered with questions as to why apparently superior technology failed to capture the market; perhaps the classic case is the VHS-v-Betamax struggles over videotaping. Knight recognised that sleeve valves could deliver his desired ‘unique selling point’ (reduction in engine noise) but at a cost in mechanical efficiency. It was not for the want of trying that the technology failed on land. It is possible to argue that Argylls’ collapse so shortly after their success in the Knight litigation, and the subsequent events of the First World War, contributed to the relative lack of success in developing these types of engine. In the air, many British aircraft of the early war period were powered by a third engine type, the rotary, which was initially built by French manufacturers such as Gnome, Le Rhône and Clerget or their British licence-holders. Perhaps it was felt that developing too many different types of engine (rotary, in-line poppet-valve and sleeve-valve) would place an unacceptable training burden on an already stretched corps of mechanics, and reduce the effectiveness of the war effort. After the war, the efforts of Wallace (Glasgow) Ltd. in the 1920s still failed to provide the breakthrough on land or water, and by this time poppet valves had developed sufficiently to gain a stranglehold on car engine applications. There is no doubt that Archie Niven’s presentation in 1926 anticipated that aero engines could be the future niche for sleeve-valve technology, but US companies failed to capitalise on this. Eventually, British success in the shape of the Bristol series led to an engine which, by all accounts, ran like the proverbial sewing machine
Fig. 5. Bristol Type 170 Freighter, RAAF Museum, Point Cook, Melbourne. Photograph Ó S. Adams, 2008, used with permission.
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and could have had an enormous impact on land vehicle powerplants if adopted, but by that time it was too late. The car industry has apparently concentrated more effort on advanced diesel technology, and even innovations like the rotary Wankel engine have had little success [21]. I would like to conclude this article with mention of a personal link. As well as its use in famous wartime aircraft, the fully-developed Bristol Hercules model 734 engine, which produced 1980 h.p., was fitted to a much later Bristol-built aircraft, the Type 170 Freighter (Fig. 5). This was operated by Silver City Airways from Lydd Airport in Kent on the cross-Channel car ferry route to Le Touquet in northern France. My father was an engineer with Silver City when I was born in Lydd, and thus it is quite likely that the first aero engine I ever heard was a Bristol Hercules developed using Burt–McCollum technology. It was certainly the first aircraft in which I flew as a passenger, in 1964. At the height of the summer season, operations ran from 07:30 to 23:00 each day and Silver City aircraft would fly multiple return trips between Lydd and Le Touquet, each sector of some 20 min flying time. The distinctive note of their Bristol Hercules engines was the backdrop to my earliest aviation experiences. References [1] Burt P, Argylls Limited. GB 190918140-A, accepted 8th August 1910. [2] Niven AM. The single-sleeve valve engine. Paper given at the meeting of the Metropolitan Section (New York) of the Society of Automotive Engineers; 15th November 1926. Partial facsimile copy. Available from:
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[9] Technical explanation derived from information provided at: http:// www.enginehistory.org/pioneering_sleeve_valve.htm [accessed 26.02.10]. [10] Cameron W, Coats A. GB 190916289-A, accepted 16th December 1909. [11] Cameron W, Coats A. GB 190926947-A, accepted 20th October 1910. [12] Hoiland E. GB 191009257-A, accepted 3rd November 1910. [13] The Times, Friday 26th July, 1912, issue 39961, p. 3, column B. [14] Knight-v-Argylls (Limited). (1912) 29 RPC 593, High Court, Chancery. [15] Knight-v-Argylls (Limited). (1913) 30 RPC 321, Court of Appeal. [16] Probably including, Burt P. Argylls Ltd. GB 191025438-A, accepted 3rd August 1911; Burt P, Matthew JS. Argylls Ltd. GB 191305683-A, accepted 20th November 1913; Burt P, Matthew JS. Argylls Ltd. GB 191307879-A, accepted 12th February 1914. [17] See the PDF copies of the original documents for addendum page, and van Dulken S. British Patents of Invention 1617–1977: a guide for researchers, p. 43–45, Section 2.21 (Extension of the patent term). London: British Library Board; 1999. ISBN 0-7123-0817-2. [18]
S.R. Adams is founder and managing director of Magister Ltd., an information and training consultancy specialising in patents documentation. He trained as a chemist at the University of Bristol, UK, followed by a Masters degree in Information Science at City University, London. He has worked in technical information since 1981, latterly with Zeneca Agrochemicals (now Syngenta) as their principal patent searcher until 1997. He has also been the editor of ‘‘International Packaging Abstracts’’, a technical searcher in the Ministry of Agriculture, Fisheries & Food in the UK, and Chair of the Patent and Trade Mark Group.