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Motor Grader Engine Air Intake System Design

 

Team Members  |  Background  |  Problem Statement
 Solution Procedure  |  Deliverables  |  Company Sponsor

 

David Gerstetter James Solberg Mark Wajda
Midlothian, IL Ottawa, IL Mt. Prospect, IL

Background

Caterpillar is currently the leading manufacturer of motor graders.  Motor graders have been traditionally thought of as leveling soil and gravel for maintaining roads.  But a very useful application of the motor grader is to remove snow from roads.  The motor grader is actually very effective during snow removal applications.  But, it has been found that when motor graders plow snow, a significant amount of snow becomes air-borne and creates a snowy swirl around the intake stack.  The intake stack is responsible for drawing ambient air into the air filter will it will eventually be used as the intake air for the engine.

Problem Statement

Caterpillar Corporation purifies the air fed to motor grader turbo-charged engines using a Donaldson multi-turbine air precleaner.  The use of this system in snow plowing applications has generated a serious problem for the motor grader operators.  The air intake is susceptible to plugging by the snow causing a loss of engine power and often the shut down of the motor grader until the filters are replaced.  The system failure typically in the following three step:. 1) The air intake becomes clogged with accumulating snow, starving the engine of its air and power, causing engine suffocation,.  2) Once air intake has sufficient snow accumulated on it, the snow and dust in the air make up a sludgy water and dirt mixture which is drawn down into the air filter canister, clogging the filters and reducing filter life, and  3) In order for this sludgy mixture to reach the filter canister it must pass through the Donaldson multi-turbine air precleaner canister.  Not only does this sludge reduce turbine efficiency, it has the tendency to freeze up the turbines when the operator shuts the motor grader down for breaks.  As a result, the problem is compounded when the turbines are frozen allowing the sludge to travel directly down to the filter canister and clog the filters.

The goal of this project is to design an air intake system that would be less susceptible to plugging during snow removal applications yet be structurally capable of withstanding vibrations experienced during the snow removal operation.

Solution Procedure

After conducting extensive research and holding conversations with Caterpillar and UIUC faculty advisors, several options were considered as possible solution approaches.

Conductive Bridge
By harnessing the heat generated by the engine exhaust through a conductive bridge connecting the exhaust stack to the engine precleaner turbine housing, the accumulation of snow on the existing Donaldson air precleaner system would be eliminated.  Additionally the conduction of heat from the exhaust stack to the precleaner turbine housing would prevent the turbine blades from remaining frozen during operation after shutdown periods.  Upon further investigation into the possible solution, this solution seemed impractical.
for a more information check out   | analysis of the conductive bridge |

Air Intake Ducked from Operator Cab
What we had initially proposed is ducting from the existing engine air intake to the operator cab and installing an air intake receptacle in the cab.  Additionally air make-up inlets would be necessary be required.  The addition of the air inlets drawing cold air in and passing it through the cab may lead to operator discomfort if the cab heat exchanger were not resized for the additional air movement.  The combination of operator discomfort and the difficulty of selling existing motor grader owners on the idea of cutting a hole in their cabs makes this a not very feasible solution to Caterpillar's problem.  Additionally, it is not an option Caterpillar is particularly fond of due to its limited application to the existing motor graders in service and the discomfort for the operator generated by the additional airflow through the cab.  We then concluded that there were better solutions to the problem then this.

Air Intake from Engine Compartment
We believe an air intake inside the engine compartment is a possible solution.  The convective heat transfer from the engine block and exhaust manifold may may be sufficient enough to melt the snow  while the inner engine compartment location would reduce the exposure of the air intake to the weather.  This option would be installed during routine pre-plowing servicing.

Initially, we were a little reluctant to pursue this possibility because Caterpillar had already tested a similar system.  Caterpillar's system took air directly in from a hole they put into the air filter.  This system still allowed the air filter to become saturated.  But in this system, the air never passed through the precleaner before going into the air filter.

Our Solution
Our solution to the problem was derived from the idea of the previous possibility.  This solution will still take the intake air from the engine compartment, but it will go through a precleaner before entering the air filter.  By going through a precleaner first, any snow or dust that is present in the engine compartment, will be ejected by the particle separator.

It was discovered that there is a air vent on top of the engine compartment and next to the intake stack.  From this vent, we plan to draw warm air through a receptacle placed on top of the vent.  From this receptacle the air is ducted through flexible tubing, and is redirected by 180 degrees before it goes into the existing precleaner.  Please refer to the graphical representation of the:

                       | Isometric Drawing |

The receptacle is essentially an up-side-down rectangular pan which covers the vent so that the warm air over the engine can be used as intake air.

Once the prototype is fabricated, we will take it out the Caterpillar's proving grounds in Peoria, IL for testing.

Deliverables

Initially, Caterpillar's specifications for our deliverables was for us to provide them with our best solution(s) to the problem.  This would basically mean that we would tell Caterpillar what we think would solve the problem.  With our ideas, Caterpillar would build prototype(s) of our proposed systems, and they would bring them up to Canada early next year (early 1998), and they test to see how effective they are.

Our actual deliverables is going to be a prototype of our single solutions along with an analysis on how it performed in our tests.  With our conclusions Caterpillar will decide if they will market our system.

Company Sponsor


Motor Grader Technical Division
27th St. & Pershing Rd., Box 1430
Decatur, Illinois 62525-1819 USA

 

 
last modified: June 9, 2005 10:18
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