ME 490: 11L Volvo MD11 Engine Configuration and Engine ...

[Pages:14]ME 490: 11L Volvo MD11 Engine Configuration and Engine Stand Design Project

By: Lucas Marshall with Jonathan Martin (Ph.D. candidate) Instructor: Professor Andre Boehman 24 April 2015

ABSTRACT The goal of this project is to provide information on how to deactivate cylinders within an engine and to design and validate an engine stand that will hold an 11L Volvo MD11 engine at the University of Michigan's W.E. Lay Auto Lab. The 11L Volvo engine is a six cylinder engine; five of these cylinders will be deactivated. This will allow many different combustion tests to be performed in the single running cylinder while minimizing fuel and fluid consumption. An engine stand was custom designed for this 11L Volvo engine and was validated through a Finite Element Analysis (FEA) on multiple loading conditions. This project is a part of the "Supertruck" program which conducts research and experiments to increase the efficiency of highway transportation by reducing petroleum consumption and lowering engine emissions.

INTRODUCTION New technologies come out each and every day, which leads to updated needs and requirements that must be continually met. For example, in the transportation sector, new requirements are being made by the US Department of Energy (DoE) to increase vehicle efficiency. One program that has been sponsored by the US DoE, Volvo, and has partners including Penn State University, Grote, and Freight Wing, is called the "Supertruck" program. This program has been around since 2011 and will continue into the year 2016. Supertruck is utilizing these new technologies to enable more efficient highway transportation vehicles by reducing petroleum consumption, lowering the customer operational cost, or reducing the environmental impact from engine emissions. The University of Michigan has joined forces with Volvo to preform advanced combustion tests with an 11L Volvo MD11 engine in the W.E. Lay Auto Lab for reducing petroleum consumption and engine emissions. A picture of the engine can be found in Figure 1. An engine stand has been designed and validated to hold this engine. A literature study has been performed on how to deactivate five of the six engine cylinders when the engine is received in the spring of 2015. Engine tests using special fuels and various combustion conditions may be performed on a small scale with this single cylinder and piston firing.

Figure 1: Volvo D11 engine [3].

SUMMARY The University of Michigan has been working with Volvo as a part of the Supertruck program. Volvo will be supplying an 11L MD11 Volvo engine to the University of Michigan in the spring of 2015 to perform advanced combustion tests. In order to accomplish these tests, an engine stand has to be designed to hold this engine and five of the six cylinders have to be deactivated so the engine can run on a single cylinder. In this report, the methods, results, and conclusions have been described in order to validate the engine stand design and to recommend how to deactivate engine cylinders.

1

METHODS A literature study was performed on cylinder deactivation to give some background information and reference on how to do such an experimental procedure. Internet research on cylinder deactivations in industry and research labs was executed using University of Michigan's Mirlyn Catalog, Science Direct, the SAE Digital Library, and Google. Research papers found have been sent to Professor Boehman and Jonathan Martin. When the engine CAD arrived from Volvo, the engine stand design began. Measurements were taken of the Auto Lab cell to insure the engine and stand would fit. Solidworks was used to design the engine stand. ANSYS was used to perform the Finite Element Analysis (FEA) tests for validation.

Literature Study A literature study was performed in order to learn how to deactivate cylinders and still run the engine on only one of the six cylinders firing (in this application). Deactivating cylinders is very experimental and there are several different ways to do it. The easiest way is to simply remove the fuel supply to all of the cylinders except one, and run the engine normally from there [1]. This will allow air to still flow through these pistons, however, no combustion of fuel will be occurring. The down side to this procedure is that there will still be compression and expansion torques caused by the air in the pistons. This could cause large torques due to the size of the engine. Another way to deactivate the cylinders is to remove the pistons from the crankshaft and seal off the non-combusting chambers [2]. In this setup, one does not have to worry about the torques in the deactivated cylinders. However, since only one cylinder is moving, there is no counterbalance to the single cylinder's motion by the other cylinders, and this could cause large torques anyways. All literature found in research will be sent to Professor Boehman and Jonathan Martin for reference.

My recommendation for deactivating cylinders allows for minimal torques on the engine from fluids and unbalanced firing cylinders. I recommend removing the fuel supply to all of the five deactivated cylinders. This requires the design of custom plenum chambers for intake and exhaust to the single firing cylinder. I also recommend cutting a hole through each deactivated piston, allowing air to flow through and eliminate compression and expansion torques [2]. This still allows all cylinders to move during the operation and counter balance each other.

User Requirements The user requirements were broken into two categories: usability and structural. The designed engine stand must be easy to use by the customer. This includes easily being able to install the engine on the stand, move the stand into and out of the test cell, and install the stand in the testing location. The designed stand must also be able to handle all structural loads produced by the 11L MD11 Volvo engine while at rest or in operation with a reasonable safety factor and fit within the size constraints of the test cell.

2

Engineering Specifications Specifications with engineering targets were created to meet the user requirements. These engineering specifications are specific to the design of this engine stand to house an 11L MD11 Volvo engine. These will also hold for most other large semi-truck engines as well. These specifications and targets can be found in Table 1.

Table 1: List of Engineering Specifications and Engineering Targets for Engine Stand Design

Engineering Specifications

Engineering Targets

Lift System Stroke

3 in.

Vertical Adjustment

12 in.

Footprint

50 x 72 in.

Engine Weight Capacity

2400 lbs.

Combined Cart Weight

3000 lbs.

Maximum Torsional Loading

> 300 ft. lbs.

Safety Factor against Yielding

> 3

Usability Engineering Targets: Engineering specifications for usability include lift system stroke and vertical adjustment. The lift system stroke of three inches is the specification for the pneumatic cylinder stroke that will attach to the caster wheels. Three inches of stroke is needed to allow the engine stand to be lifted above the ground while it is being wheeled into and out of the test cell, and then can be lowered and statically mounted into the cell during installation. A vertical adjustment of 12 inches is the maximum allowable movement by the four elephant feet that connect the engine to the stand. This vertical adjustment is required to align the axis of the engine to the axis of the dynamometer and allow them to be connected with a driveshaft. One other form of adjustability that was not listed in the table is the horizontal and lateral movement of the elephant feet. These need some adjustability to align with the mounting holes located on the engine itself.

Structural Engineering Targets: Engine specifications for the structural aspects of the stand include: footprint, engine weight capacity, combined cart weight, maximum torsional loading, and safety factor against yielding. The footprint of 50 x 72 inches is the size of the bedplate in the test cell. The stand must fit within these dimensions. The engine weight capacity is the "wet" weight of the engine, about 2400 lbs. This was found by using the dry weight of the engine (2286 lbs) and adding about 100 lbs of fluids that will be in the engine while it is running [3]. A combined cart weight of about 3000 lbs gives about 600 lbs for the weight of the engine stand itself, which was thought to be adequate. A maximum torsional loading of greater than 300 ft lbs was determined from the maximum single cylinder torque. The maximum torque the 11L MD11 Volvo engine can produce is 1550 ft lbs [3]. However, in this application, only one cylinder will be firing and producing a noticeable magnitude of torque. Dividing this max torque value by six

3

(the number of cylinders) will give us the maximum single torque of about 258 ft lbs. A safety factor of greater than three was determined to be adequate for this application. Previous Design A similar design project was performed by a University of Michigan ME 450 team named Shake N' Bake in the winter 2013 semester. Figure 2 shows a Solidworks model of this team's engine stand design. This engine stand was created for the same reason to allow for a simple and easy way to mount and install an engine in the auto lab. It was designed with very similar user requirements and engineering specifications. However, the engineering targets are slightly different for the structural aspect. This engine stand was designed and validated for engines weighing up to 1000 lbs. The pneumatic cylinders have a total capacity of 2262 lbs at 80 psi and the caster wheels have a total capacity of 2800 lbs. These load capacities are not large enough for the 11L MD11 Volvo engine, so this engine stand has to be re-designed and validated for this larger engine. Figure 2: Previous ME 450 team's engine stand design shown in Solidworks.

RESULTS AND DISCUSSION This section will go into detail of the engineering work performed to design and validate a new engine stand to hold the 11L MD11 Volvo engine. A discussion of the results will conclude if the engineering targets have been met. Since the total scope of this project is not complete, a section of future work will show what still needs to be completed before combustion tests can be performed with the engine. Engine Stand Design One of the biggest constraints on this design initially was the size of the engine. The test cell where this engine and stand will be installed at is a smaller cell. The bedplate is 50 x 72 inches,

4

which gave a very strict constraint. The engine itself is 54 inches long and 44 inches wide [3], add some additional length and width on the stand to contain this engine, and a driveshaft has to be attached between the rear of the engine and the dynamometer, and there is not much extra space left over. Because of this, the front of the engine will be overhanging the bedplate by a few inches (as seen in Figure 3). This is okay; there are still a couple feet of space to get around the front of the engine in the test cell. From measurements taken at the beginning of the semester, the engine stand should be able to fit in the test cell.

Figure 3: Final engine stand design for the 11L MD11 Volvo engine as shown in Solidworks. The red "cones" are the elephant feet that the engine will mount to.

Structure Redesign: The biggest design change to the engine stand was the additional cross beam added to the center of the stand, adding two additional bed plate mounting blocks. This was added due to the oil pan on the Volvo engine. This oil pan will be resting just several inches above the bedplate itself while it is mounted in the cell. Because of this, it would have interfered with the front crossbeam. Since this crossbeam had to be removed, an additional crossbeam was added behind the oil pan for structural integrity. The redesign from the oil pan does decrease the adjustability of the elephant feet on the design. However, there is still plenty of adjustability for this application to mount the engine.

Cylinder and Caster Resize: The Bimba pneumatic cylinders and caster wheels were both increased in size due to the weight of the Volvo engine. The initial cylinders (3 in diameter, 3 in stroke) only could provide a force of 566 lbs per cylinder, or 2262 lbs total at 80 psi air supply. This was calculated using Equation 1. Adding two additional cylinders would provide a lift force of 3396 lbs. Having a total engine and cart combined weight of about 3000 lbs, this does not give a comfortable safety factor since the engine could be rolling around on uneven or bumpy surfaces. The pneumatic cylinders were bumped up one size to 4 in diameter, 3 in stroke. This gives a total of 6032 lbs of lift (using Equation 1) for all six cylinders at 80 psi, which gives a comfortable safety factor of 2 for this application. The caster wheels were also increased from an

5

initial capacity of 700 lbs to a capacity of 1000 lbs. This will also give a safety factor of about 2

for all six casters on the stand.

=

2 4

(Equation 1)

Where Flift is the lift force provided by the pneumatic cylinder, P is the air supply pressure, and

D is the diameter of the cylinder.

Engine Stand Validation The redesigned engine stand had to be validated for its structural integrity to prove that it could handle all loading cases that the engine would produce. This was completed using ANSYS to execute a Finite Element Analysis (FEA) on each loading case. These tests included: an initial analysis on what was thought to be the greatest beam bending, the wheel caster loading, and the live load. A500 steel was used for simulation; this material will be used for the actual manufacturing of the engine stand as well. A500 steel has a density of 0.2384 lb/in3, yield strength of 45,700 psi, and ultimate tensile strength of 58,000 psi [4].

Initial Beam Bending: Before too much work was put into the FEA and engine stand design, a simple beam bending test was performed at what was thought to be the greatest bending arm in the stand. This was to confirm that the level of support used in this application would be adequate. The beam chosen was at the rear of the engine where two of the elephant feet were mounted. Figure 4 shows the displacement results of this beam. These results were determined by applying a quarter of the dry engine weight to each elephant foot (571.5 lbs each), and the crossbeams in the opposite direction were fixed in place. Maximum displacement was found to be 0.0025 inches located at the center of the beam which is negligible. A von-Mises stress analysis can be found in Appendix A.1. Results from the stress analysis shows us a maximum stress of 3600 psi, which gives us a safety factor of 12.5.

Figure 4: Deformation FEA results on rear engine crossbeam. Maximum displacement found to be 0.0025 inches at the center of the beam.

6

Caster Loading: The next simulation does an analysis of the engine mounted to the stand resting on the casters, but not installed in the test cell yet. This would be when the stand is in storage outside of the cell, or being wheeled into or out of the test cell. Shown in Figure 5 is a von-Mises stress analysis of the engine "resting" on the casters. The entire dry weight of the engine (2286 lbs) was distributed evenly among the four elephant feet. There are four mounting holes for each of the six cylinders that were rigidly fixed in space to simplify this simulation. The maximum stress is found to be 13,600 psi at roughly each of these cylinder mounting holes, giving a safety factor of about 3.4. This is a little lower than we would like, but it does meet the engineering target. We believe that this safety factor would increase to 4 or 5 in the real life application. This is because there are increased stresses occurring from stress concentrations in the simulation. These stresses would be spread out by the cylinder and washers above and below the steel plate in the real application. A FEA test of the total deformation for this simulation can be found in Appendix A.2. Maximum displacement was found to be 0.0043 inches at the rear engine mounting crossbeam, this value is negligible.

Figure 5: Von-Mises FEA results on entire engine stand. Maximum stress found to be 13,600 psi located at stress concentrations where the cylinder mounting holes were rigidly fixed in place.

Live Load: A simulation of the greatest load that would be caused by the engine was performed. This is while the engine is installed in the test cell and running. The "wet" weight of the engine (2400 lbs) is distributed evenly among the four elephant feet, and a maximum single cylinder torque is added to the simulation as well. This max cylinder torque was calculated using the free body diagram shown in Figure 6. The single cylinder torque of 260 ft-lb is divided evenly to each elephant foot. This torque is divided by the distance the elephant foot is from the center engine axis (in feet). This force is then subtracted from the elephant feet on the right, and added to the elephant feet on the left.

7

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download