Monoblock engine
The term monoblock engine nowadays mostly means an internal combustion engine in which
- The cylinder bank , cylinder head and part of the crankcase are cast in one piece.
A monoblock can also mean the following design:
- Cylinder bank and cylinder head in one piece, but separated from the crankcase.
- Cylinder bank and crankcase in one piece, but with a separate cylinder head.
Since the latter is the standard today, monoblock now mainly refers to the engine where all three features can be found in one cast.
This design was particularly popular in the 1920s for use in racing engines, when gas sealing at high combustion pressure was a critical limit for performance development. Modern multi-layer steel seals later solved this problem for engines with separate cylinder heads.
The monoblock also made it possible to achieve greater rigidity of the crankcase and the cylinder banks, which was particularly beneficial in terms of speed stability.
Fixing the cylinder banks on the crankcase could also lead to material fatigue and cracks in non-monoblock engines. By means of numerical calculation methods for optimizing the head-block association with regard to the introduction of force and the resulting liner distortion, similar performance can now be achieved without a monoblock.
advantages
- Higher compressions, as not restricted by the cylinder head gasket because the cylinder and head are made from one cast.
- Temperature resistance, as the cylinder head gasket cannot burn (with earlier cork, leather, rubber and paper gaskets).
- Higher reliability, as it is impossible for the cooling water to enter the cylinder through a defective cylinder head gasket, which in other engines can lead to broken connecting rods, pistons or damaged valves.
- Rotational speed stability as the crankcase is stiffer than a screwed-on crankcase due to the integral cylinder bank
- Less chance of cracks forming, as the introduction of force from the cylinder head bolts into the cylinder or the crankcase does not have to be taken into account.
disadvantage
- Very complex milling of the valve seats, as this has to be done from below through the crankcase and cylinder.
- Elaborate post-processing of the cast part, since the engine block has to be milled flat on both sides in order to seal the mostly open-cast cooling jackets with a waterproof cover.
- Limited options for optimizing the shape of the combustion chamber, as the valves can only be arranged in parallel and not at an angle, especially in long-stroke engines.
- Very costly maintenance, since the entire engine including the oil, crankshaft etc. has to be dismantled to clean the valve seats or to replace a valve or to re-mill the valve seat.
development
The technical starting point of the internal combustion engine at the beginning of the 20th century was the sack cylinder , which was screwed individually or in pairs onto a crankcase .
The first engine to be designated as a monobloc is the 7-liter engine installed in the 1912 Peugeot L76 Grand Prix racing car. Not a real monoblock in today's sense, because the cylinder head and cylinder bank consist of a gray cast iron part, but they are placed on an aluminum crankcase. Nevertheless, this was a great achievement, which already anticipated hanging valves, double overhead camshafts, multi-valve technology, etc. and served as an inspiration for many post-war designs.
After the First World War, Walter Owen Bentley launched a 3-liter monoblock engine with a combined cylinder, cylinder head and upper crankcase made of gray cast iron around 1921. The engine of the Leyland Eight, which was built from 1920 to 1923, also had a monoblock.
In the USA Harry Miller developed a monoblock as early as 1916 that even included the entire crankcase. He achieved this by using a two-part, triple ball bearing crankshaft in a so-called tunnel crank . Later models of the engine included wet cylinder liners and a removable cylinder head and were used successfully in various racing vehicles. His former employee Fred Offenhauser continued to build engines based on the monoblock principle, which dominated the Indy 500 race until well into the 1970s (last race in 1982 in Jim McElreath's Eagle chassis ).
In the 1920s, other European manufacturers such as Bugatti , Mercedes , Ballot, Sunbeam and Voisin relied on closed cylinders with a one-piece head, but used separate, bolted-on crankcases. The American manufacturer Duesenberg went the opposite way of the one-piece crankcase with attached cylinders and separate head.
In the 1930s, racing engines began to optimize the shape of the combustion chamber, which resulted in angled valves and inevitably removable cylinder heads. This is what happened, for example, with the engine of the Alfa Romeo P3 and with the engines of the Silver Arrows from Auto Union and Mercedes .
In the aircraft engine sector, the monoblock was once again used due to its great robustness, despite the high costs of an engine revision. The different versions of the Rolls-Royce Merlin aircraft engine were varied, sometimes with a cylinder bank with an integral crankcase and removable cylinder head (PV-12 to Merlin B), but also with an integral cylinder head (Merlin G). Ultimately, from 1941 onwards, a variant with both separate cylinder head and crankcase prevailed, which was first manufactured by Packard Motor Co. in Detroit, USA.
German aircraft engines in World War II, such as the DB600 , 601, 605, continued to rely on integral cylinder heads, although the crankcase was only bolted to the cylinder banks using the cylinder liners.
Monoblock engines at Honda
With the GC series, Honda offers a number of small stationary engines that have a monoblock design. Honda tries to get by with fewer cast parts in order to save production costs and even leaves out the pressed-in cylinder liners made of steel by simply running the pistons directly in the coated aluminum block. What is remarkable about the design of the GC motors is that the toothed belt for driving the camshaft also runs inside the monoblock. The crankcase is not separated horizontally as usual, but diagonally. One of the two main crankshaft bearings is located in the monoblock on the fan side, the second main bearing on the output side is located in the oil pan.
Monoblock engines at Steyr Daimler Puch
The forerunners of Steyr Daimler Puch AG, the Österreichische Waffenfabriksgesellschaft , had the first monoblock engine in use as early as the 1920s (type Steyr II , gasoline engine).
In 1976 AVL List GmbH presented the concept of a light diesel engine (LD). Steyr Daimler Puch and Bayerische Motoren Werke AG founded BMW - STEYR Motorengesellschaft mbH, the purpose of which was to bring this light diesel engine into series production. It was called the "M1" engine type. After the license was granted, the development partners started with the construction and procurement of so-called pre-development prototypes (VEP) of four- and six-cylinder engines, of which, in turn, various construction stages were further developed and procured.
It was the first car engine with direct injection , mechanical pump-nozzle injection elements (Patent Steyr Daimler Puch AG), charge air cooling, exhaust gas turbocharging and a new acoustic concept (wet capsule, dry capsule). The M1 could not be fully developed within the project timeframe. The company shares of Steyr Daimler Puch AG were taken over by BMW in 1981. From then on BMW developed swirl chamber motors (series production started in 1983), Steyr Daimler Puch further developed the M1 itself (from 1983 in Steyr Motorentechnik GmbH).
The M1 motor went into small series as a boat engine in 1990 for the American marine engine manufacturer Outboard Marine Corporation . Mention should be made of the licensing of the Russian manufacturer GAZ ( Gorkowski Awtomobilny Sawod ) in 1998, who built over 50,000 4-cylinder monoblock engines by 2007 (used in the GAZ GAZelle or Volga vehicles, among others ). The M1 is present in the marine and military applications market today. The Steyr Motors GmbH is building it in the 4- and 6-cylinder version with up to 225 kW, a version with 135 kW is already after the emission standard Euro 5 certified.
At the end of 2009, at Defense & Security Equipment International in London, the working prototype of a V8 engine based on two inline four-cylinder monoblocks (72 ° bank angle) with a provisional output of 250 kW was presented.
At the end of 2010, the prototype of a completely redesigned two-cylinder monoblock engine with a pump-nozzle injection system was presented at the Marine equipment trade show (METS) in Amsterdam. This engine is to be used as a unit for sailing boats, tanks and subsequently as a range extender for the automotive sector. 25 kW electrical power was named. This motor has a complete balance of the oscillating masses. Series development was completed in 2013.
2014 began a new era of the monoblock engine from Steyr Motors GmbH.
The 2-cylinder engine (M12CR) was redesigned and developed as a common rail engine. Nominal power 40 kW, emission level EURO5.
The 4-cylinder engine (M14CR) was redesigned and developed as a common rail engine. Nominal output 110 kW, emission level EURO5.
Individual evidence
- ^ The World's Greatest Racing Car . In: Enthusiast Publishing Ltd (Ed.): The Automobile Magazine . tape XXVII , no. 13 . The Automobile Magazine, New York September 26, 1912, pp. 607-612 .
- ^ Stein, Ralph, 1909-1994 .: The greatest cars . Simon and Schuster, New York 1979, ISBN 0-671-25195-3 .
- ^ Posthumus, Cyril .: The story of veteran & vintage cars . Hamlyn, London 1977, ISBN 0-600-39155-8 , pp. 76-77 .
- ↑ Harry Miller's first masterpiece, a SOHC 16-Valve - Four Cylinder Engine | The Old Motor. Retrieved November 22, 2017 (American English).
- ^ The Revs Institute | 1919 ballot. Retrieved November 23, 2017 (American English).
- ↑ J. SJ. Wells: The Rolls-Royce Merlin Aero Engine Early Development 1933–1937: The Ramp Head Merlin. In: Torque Meter Magazine. Aircraft Engine Historical Society, 2006, accessed November 23, 2017 .
- ↑ Honda Engines | GC160 4-Stroke Engine | Features, Specs, and Model Info. (No longer available online.) Archived from the original on January 9, 2015 ; accessed on November 23, 2017 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Shohei Kono, Honda Motor Co Ltd, Honda Motor Co Ltd: Overhead camshaft engine . December 28, 2016 ( google.com [accessed November 23, 2017]).
