The Yanmar Holding Company Ltd was founded in its current form in 2013, but the company has a long history of manufacture stretching back over 100 years to the production of its first gas engine. Originally named Yamaoko Hatsudoki Kosakusho, it progressed quickly into oil engines and adopted the Yanmar name in 1921. Its first marine engine was launched in 1925, designed for fishing boat applications.
Since that time, Yanmar has grown dramatically and, at the end of March 2015, was supported by more than 17,000 employees worldwide. Despite its strong manufacturing base in Japan, Yanmar has been proactive globally, with earlier ventures including the establishment of a facility in Brasil during 1957. It also now has Far East subsidiaries in Thailand, Indonesia and China as well as European and North American operations and quotes its business domains as including agricultural machinery, construction equipment, energy systems and component manufacture. These are in addition to its well establishes industrial and marine engine operations, which offer both high-speed and medium-speed products for a variety of applications. These include workboats and high-speed craft, but the company also has a strong market in engines and drives for pleasure craft.
Yanmar’s Marine Operations Division specialises in developing and producing small and medium-sized diesel engines and, for high-speed engines, its global hub factory is the Tsukaguchi plant in the Hyogo prefecture of Japan. The plant uses a cell production system that allows full control over engine builds with, in many cases, all assembly work being carried out by one technician. The result is a consistent build quality that ensures fault free operation and reliability in service. The plant maintains consistent quality control systems over a wide range of diesel engines and has gained certification from seven major classification societies including Lloyds Register of Shipping and the American Bureau of Shipping, as well as Japanese NK approval. Different engine types carry approvals from different societies, depending on their vessel applications and which happens to be the most appropriate society.
Having focused on smaller vessel needs, the Yanmar high-speed propulsion engine range starts with its CHE series products, offering models with shaft outputs from 57kW to 208kW. The largest of these engines, the 3CH-WUTE, is governed by IMO requirements and meets IMO II emissions limits. Engines offer good torque characteristics at higher speeds and also have a high capacity power take-off facility at the non-drive end. A propeller shaft half-coupling is provided as part of the standard scope and a trolling device is available as an option. In order to minimise maintenance times, large ports are provided in the cylinder blocks to enable in-situ replacement of pistons. Cylinders also use wet liners, which offer both longer life and lower rebuild costs.
Higher power requirements can be met by the Yanmar AY series of engines. These are available in six- and 12-cylinder configurations, with the highest output of 1,340kW being delivered by the 12AYM-WGT, running at a shaft speed of 1,940 rpm. This product, in its latest generation, has been developed as an ‘Eco Diesel’ to satisfy IMO II requirements for lower NOx emissions but fuel consumption has also been improved and smoke generation has been reduced. A number of features have been introduced to achieve this including an internal exhaust gas recirculation system, which does not require any external control devices or significant change to the engine. Recirculation is facilitated through control of the lift and timing of intake and exhaust valves, with partial reverse flow of exhaust gases air back into the cylinder from the common exhaust manifold.
The AY engine has been developed based on long-term experience gained from 12LA and 16LA series engines, first put into service in the 1980s and operating in more than 2,000 global installations. Many performance improvements have been derived from a new combustion system, which uses an all-new design of fuel injector. This features multiple micro-sized injection holes to produce both a finer fuel mist and a staggered injection pattern, thus improving the combustion process. Deeper combustion chambers have been introduced, along with re-profiled cylinder heads, and the air intake port geometry produces a swirl or votex flow into the combustion chamber, which promotes better fuel-air mixing. Combustion efficiency is therefore improved, as is engine specific power capability. Compared with the previous equivalent engine, typical fuel savings are estimated as being 10g/kWhr, or around a 5 per cent reduction in fuel burned for the same power output.
The long-stroke AY series has low lubricating oil consumption levels and long overhaul intervals due to the use of a special ceramic surface treatment on cylinder liners. The process embeds Silicon Carbide onto the wear surface increasing its hardness and give the liners superior wear resistance and durability. Combined with the use of nitrided stainless steel piston rings and tight clearances between the piston and liner, leakage past the piston rings is minimised. The engine also has an optimised flywheel weight, water-cooled exhaust manifold and is designed to be leak-free; an increasingly important aspect with new rulings on oil spills now introduced in some waters. From a maintenance perspective, the engines are again designed for in-situ piston replacement and cylinder heads are individual. Yanmar has also retained a mechanical engine management system to avoid risks of failure of delicate electronic equipment in often restricted and hot marine enginerooms.
For higher propulsion powers, Yanmar offers a range of medium-speed, in-line engines capable of delivering powers of up to 3,310kW from its largest product, the 8N330W, running at 620 rpm. 6EY engines are available at ratings from 374kW to 1,920kW, the latter running at 750 rpm, with 8 cylinder variants increasing power available to 2,560kW at the same shaft speed. 6N330W engine ratings are available from 2,207kW to 2,574kW and the eight-cylinder variant offers power options of 2,942kW, 3163kW and 3,310kW. These engines feature the same combustion technology as high-speed products, and also use Miller timing to finish the intake stroke earlier and allow air delivered by the high-pressure turbocharger to expand, reducing its temperature before the compression stroke and subsequent combustion, this reducing NOx formation. All engines are equipped with reduction gearboxes for either fixed or variable pitch propellers, depending on the individual engine specification.
To complement its propulsion engines, Yanmar manufacturers auxiliary gensets for the marine market, using in-line engines in packages offering electrical outputs from 180kWe to a maximum of 3,300 kWe. These engines are manufactured within Yanmar’s Amagasaki plant, which forms part of its Large Power Plants Operations Division. First opened in 1936 as a small diesel engine plant, it progressed to become a mass production facility for diesel and gas engines for ship propulsion, land applications and general use. The plant received ISO 9001 certification from Lloyds Register in 1992. The company develops its own technologies and also maintains integrated manufacturing principles, building many components within its own factories rather than being dependent on suppliers for key engine parts.
Yanmar is experienced in building marine engines in smaller volumes, but its reputation has also been enhanced through high volume production of high-quality engines for road and agricultural vehicles. Reflecting this, the company announced the delivery of its 10 millionth diesel engine in 1992 and, in August of this year, its Biwa Factory alone announced the production of its 5 millionth industrial diesel engine since its establishment in 1995. Production from this plant includes the Yanmar TNV model diesel engine, developed to minimise environmental impact and deliver enhance performance. The company’s environment credentials are notable and it was first manufacturer in the world to be certified by the California Air Resources Board for diesel engines in the range 19 to 56kW, compliant with Tier 4 standards, also receiving certification from the US Environmental Protection Agency. Another first, in 2013, was Yanmar’s approval by the Swiss Federal Office for the Environment for engines in the 19~37kW class, under the world's strictest diesel engine regulations.
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