The use of transparent prototypes or windows in specific regions
of the transmission makes it possible to visualize, at least partially,
the flows and distribution of the lubricant within the transmission,
and to understand whether it reaches the various components.
Similarly, by means of a physical prototype and bench tests, it
is possible to verify the correct positioning of the breather ducts,
which must be adequately protected in order to prevent the
escape of the lubricant, and the functioning of the transmission
under different operating conditions, for example by changing
inclination, number of revolutions, or direction of rotation.
These are some of the issues faced daily by those who design and
build transmissions of all kinds, from the automotive and industrial
sectors to the aeronautical sector; from small transmissions to
those for the naval and wind-power sectors.
However, waiting for an advanced stage of the project (i.e.
once you have a prototype on the bench) to address the issue
of lubrication can present surprises that can significantly impact
both the development time of the transmission and its cost.
Discovering that some vital components, such as bearings, are not
properly lubricated, or that there are oil leaks from the vents may
require design changes, which can be costly at this late stage. In
addition, there are some machine operating conditions that cannot
be or are difficult to test on the bench, such asdynamic braking,
acceleration, or particular temperature conditions.
To address these issues and to reduce the risks, costs and
development times of transmissions, more and more companies
are shifting the issue of “good lubrication” from the experimental
verification phase to the actual design phase.
This has come about thanks to the availability of new numerical
simulation technologies that enable the use of a virtual bench to
test different operating and lubrication conditions quickly, and
especially before building a physical prototype.
Models of this type complement and complete experimentation
and, if used in the preliminary stages of the design, allow
the project to be directed correctly and prevent lubrication or
overheating problems.
One of the companies that has adopted these numerical simulation
methods is Comer Industries.
Comer Industries, based in Reggiolo in the province of
Reggio Emilia, is the leading global player in the design and
production of advanced engineering systems
and mechatronics solutions for power
transmission. The company operates in the
fields of agricultural machinery, construction
and forestry equipment, energy and industry.
Founded in 1970 by the Storchi family, today
the company is led by the second generation.
The president and CEO is Matteo Storchi.
Comer Industries has 1400 employees,
exports to all 5 continents and has 7 offices
in Europe, 1 in the United States, 1 in Brazil, 2
in China and 1 in India, including production
plants and commercial branches it reaches
54 countries with its products and in 2020 it
registered has a net turnover of 396 million
euros. In March 2019, the company opened to
external investors by listing on the Milan Stock
Exchange’s AIM market.
Comer Industries is one of most important suppliers of the most
relevant world players in the construction of agricultural, industrial
and renewable energy machinery. The mechanical components
made by Comer Industries represent crucial elements for the
correct functioning of combine harvesters, tractors, plows,
mowers, round balers, excavators, bulldozers and wind generators.
The market on which Comer Industries works is perfectly
globalized and competition has imposed the ability to ensure
customers products and assistance services with unique standards
of excellence in every part of the world.
One of Comer Industries’ numerical simulations for lubrication
concerned predicting the path of the oil in an axle with an
integrated planetary gear system input stage for a compactor.
During its operations, the compactor frequently travels uphill and
downhill. The lubrication of the planetary gears is critical in these
phases and must be guaranteed, as must the correct exchange of
oil between the planetary gears and the axle to avoid dangerous
increases in temperature.
Since the planetary gear system and the axle communicate via two
oil passages, the analysis aimed to optimize the geometry of these
two passages by recreating a meaningful operating condition in a
single simulation consisting consecutively of a horizontal machine
path phase, an uphill, a downhill, and a horizontal phase to return
to the starting point.
All internal components of the axle and planetary gear system
were included in the model along with two variants of the housing:
the first with the existing oil passage geometry and the second
with some proposed optimized oil passages. Finally, the oil
was modeled at its working temperature properties: the model
consisted of about six million particles.
The results obtained were very interesting and made it possible
to evaluate:
- the oil redistribution between the two oil passages both
qualitatively and quantitatively in terms of oil flow rates
- how this redistribution changes in the various phases -
horizontal, uphill and downhill
- how the previous stage of the path affects the next stages,
and how the oil behaves during transitions
It was found that, with the same oil quantity, the geometry of the
current passages does not allow the oil to reach the planetary
gears in all the configurations, thereby the oil exchange between
the two environments is insufficient.
On the other hand, by enlarging and shaping the passages
differently, it was possible to guarantee a greater flow of oil
to the planetary gears and to ensure an adequate exchange
of oil between the axle and the planetary gears that can avoid
temperature raise.
This analysis was validated experimentally with some specific
tests on a test bench: a high correspondence was obtained during
the same work cycle (with the same inclinations) when comparing
the simulated dynamic oil level with the experimental one.
This made it possible to implement the modifications to the oil
passages without carrying out multiple experimental iterations
which, since they affect the casting models, would have resulted
in excessive time and costs related to potentially numerous
remakes of equipment and components. In addition, there was no
need to increase the oil level, so efficiency could be preserved.
EnginSoft wishes to acknowledge “Il Progettista
Industriale” which first published this article in its
magazine in April 2021.
Newsletter EnginSoft Year 18 n°2
By Elisabetta Fava | Comer Industries
Massimo Galbiati | EnginSoft
