In December, Kubota reached the impressive 20 millionth milestone in production of compact industrial engines. This was accomplished over a period of some 80 years and the company has earned a reputation as a consistent innovator in design and production of compact multicylinder diesel engines. Kubota reached the 10 millionth production milestone in 1987 and it has doubled that in the last 15 years.
We joined Kubota to celebrate its new production record and for an update on its latest developments, meeting in Osaka with Yoshiaki Namboku, general manager of the engine division.
"For many years we focused only on captive engine production," Namboku related. "It was in 1975 that we began producing engines for other OEMs and that has been very important in strengthening the company's technical and production base.
"Our niche is special, but we are very modern in our methods and can attract the best engineering talent. We have a very strong position and certainly feel our best years are still ahead of us. At the same time we are extremely proud of our past and the contribution and commitment of our employees. Our technology is known around the world.
"We have a new motto at the engine division. 'Your Driving Force -- Kubota Engine' That's what we are for our OEM customers and our captive customers. We want them to know they can depend on us now and in the future. We will face every challenge together."
The Kubota diesel engine range currently runs from 10.5 to 86.7 hp (7.9 to 64.7 kW). At the top of the range is the relatively new V3300 Series, which has a displacement of 3.318 L. Below that is the 03 M Series, which runs from 1.393 to 2.434 L displacement. Dropping down another range is the 05 Series, with displacements from 0.898 to 1.498 L. The smallest range is the Super Mini Series, which run from 0.479 to 0.778 L.
In recent years Kubota has been extending its power range upward, as demonstrated by the V3300 introduction in 1997. But in the case of the all-new Z602 diesel, this engine fits into the Super Mini engine range between the two-cylinder Z482 and threecylinder D722.
The Z602 is a two-cylinder, four-cycle, water-cooled IDI unit with a bore and stroke of 72 x 73.6 mm and swept displacement of 0.599 L. It has two valves per cylinder. The Z602 is rated 13.8 hp (10.3 kW) at 3200 rpm, and another version coming later this year will be rated 15.5 hp (11.6 kW)at 3600 rpm. The compression ratio is 24:1. Dry weight is 132 lb. (60 kg).
Importantly, the Z602 has the same width and 20 mm lower height compared to the Z482. Though it is 24 mm longer, for most applications the footprint and mounting locations are almost identical. This allows OEMs to step up nearly 25 percent in power without re-engineering their existing machines, the company said.
The Z602 offers improved performance. This has been achieved through optimization of Kubota's three vortex combustion system. The use of a builtin closed breather assembly is scheduled for Tier II compliance.
The bore and stroke of the Z602 have been increased compared to the Z482 without impacting the overall height or width through the used of a partially extended cylinder block and an oil pan with greater length, but less height. The result is greater power density for the Z602 comparing the overall output to the overall envelope.
The Z602 is also quieter than the Z482 and this has been achieved through the use of a partially floating head cover, a moly sulfide MoS2 coated piston, and a counterbalanced forged crankshaft. The piston uses a three-ring pack, with a half keystone compression ring, an undercut middle ring and a two-piece spring expander design for the oil control ring. The top ring is a nitrogen hardened steel ring. The second is chrome plated. The bottom ring has dual lands and is also chrome plated. The piston is 2.8 mm shorter than the piston for the Z482 which partially accounts for being able to accommodate the longer stroke without increasing the overall engine height.
Reliability and durability of the Z602 are also improved, Kubota said. The Z602 has a drilled cooling passage between the two cylinders and this lowers piston and piston ring temperature approximately 68[degrees]F (20[degrees]C).
According to Namboku, Kubota is seriously considering a three-cylinder version of the Z602, which would have a displacement of 0.898 and output of approximately 20.6 hp (15.4 kW) at 3200 rpm. That could probably be accomplished, again, without increasing the width and height of the engine envelope. It would obviously be somewhat longer in length.
"Looking ahead," said Namboku, "our next challenge will be how to meet future worldwide emission regulations.
"The difficult thing is to meet the standards with minimal cost. We have a range of options under consideration. That includes optimized combustion, high-pressure injection, electronic engine control, exhaust gas recirculation (EGR) and so forth.
"We are conducting extensive research on all of these technologies. We have confidence in our technical base and we will continue to develop engines meeting emissions requirements."
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1 comment:
Thanks for sharing.
Kubota engines have made a trusted reputation and long history for out of the box and in field quality and durability. The Kubota Super Mini Series has become the benchmark in the compact diesel engine market. Country sales and services are the premium providers of super mini series kubota diesel engines. They are developed to provide a compact, fuel efficient, and clean power solution.
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