John E. Beard

The effects of the generating pin size and placement on the curvature and displacement of epitrochoidal gerotors

Abstract Gerotors do not have auxiliary gears in general, therefore the motion of one lobed gear relative to the other lobed gear is produced by the forces between the two contacting lobes. The contact forces, however, result in wear in one or both lobed gears which, in turn, reduces the life of the mechanism. As a gerotor cannot be adjusted to compensate for the wear, it is important that the contact forces be kept to a minimum. It is well known that the wear rate can be reduced by decreasing the curvature (or increasing the radius of curvature) of the lobes. The curvature is a function of the size and the placement of the pins which generate the lobe shape. In this paper, relationships are derived which show the influence of the trochoid ratio, the pin size ratio, and the radius of the generating pin on the curvature of the epitrochoidal gerotor. The relationships provide geometric insight into the design of gerotors which can save time and effort in the manufacturing process. In addition, the results are combined with previously published formulate for the pocket displacement to obtain design charts. These charts can be easily used by the designer to predict the effect of the geometry on the performance of a gerotor. An example is presented, which shows how a commercially available gerotor can be modified to give a 48.7% increase in the minimum radius of curvature with only a 3.2% decrease in the displacement and no change in the overall size of the gerotor.

Force analysis of the apex seals in the wankel rotary compressor including the influence of fluctuations in the crankshaft speed

This paper derives equations for the radial and transverse components of the acceleration of an apex seal in the rotor of a Wankel rotary compressor. Then the equations are modified to include the effects of two cyclic fluctuations in the crankshaft speed during start-up and a simple harmonic fluctuation in the nominal operating speed. Following this, we investigate a dynamic force analysis of the seal including the friction forces between the tip of the seal and the housing and between the side of the seal and the rotor. The investigation shows that the effects of the friction between the side of a seal and the rotor are insignificant. Therefore, ignoring this friction, plots are presented for the housing force and the normal force as a function of the crank position and the fluctuation in the operating speed for a specified trochoid ratio. The plots show that realistic values of the fluctuation in the operating speed do not have a significant effect on the forces acting on a seal and can, therefore, be safely neglected. Plots are also presented for the two forces, for a specified fluctuation in the operating speed, against a specified range of the trochoid ratio and different positions of the crank. Finally, for a specified trochoid ratio, the two forces are plotted against several values of start-up time as the compressor accelerates to the nominal operating speed with a constant acceleration.

An interdisciplinary program for education and outreach in hybrid & Electric Drive Vehicle Engineering at Michigan Technological University

The automotive industry is in a transformation towards powertrain electrification, requiring automotive engineers to develop and integrate technologies from multiple disciplines. Michigan Technological University is rolling out a new program in interdisciplinary master of engineering degree and graduate and undergraduate certificates in Advanced Electric Drive Vehicle Engineering. Distinctively we are focusing our education program at the vehicle level and the interconnection to the electric grid. The vehicle level aspects of the program include vehicle requirements, integration of propulsion technologies, safety, diagnostics, control and calibration. Michigan Tech and our industrial partners see these as critical limiting factors in the development and production of advanced electric transportation systems. Additionally, the effort leverages the existing distance learning program in electric power. The result are an interdisciplinary program that meets the needs of the transportation and power industries and provides students with a unique skill set that will accelerate the Introduction

Comparison of helical and skewed axis gerotor pumps

The gerotor is a planar mechanism consisting of two surfaces whose relative motion can be described by the kinematics of orbiting pitch circles. Typically, gerotor surfaces are prismatic with the axes of rotation parallel to the ruled surfaces. For a given position, the generated cross section of the mechanism in the plane of motion is independent of the location of the section along the axis of rotation. In this work, a mathematical derivation for producing gerotors with non-prismatic surfaces is presented. The implementation results in two types of gerotors, mechanisms with conical surfaces relative to the rotor axis, and mechanisms with helical surfaces. These are relatively new inventions and this is the first publication of the mathematical model describing these mechanisms. The derivations of the mathematics associated with each mechanism are presented. Comparisons of the mechanisms are presented based on the displacement, compression ratio and surface area to volume ratio.

Recovery Act - An Interdisciplinary Program for Education and Outreach in Transportation Electrification

1) How the project adds to the education of engineering students in the area of vehicle electrification: This project created and implemented a significant interdisciplinary curriculum in HEV engineering that includes courses focused on the major components (engines, battery cells, e‐machines, and power electronics). The new curriculum, rather uniquely, features two new classes and two new labs that emphasize a vehicle level integration of a hybrid electric powertrain that parallels the vehicle development process used by the OEMs ‐ commercial grade software is used to design a hybrid electric vehicle, hardware‐in‐the‐loop testing is performed on each component until the entire powertrain is optimized, the calibration is flashed to a vehicle, ride‐and‐drives are executed including on board data acquisition. In addition, nine existing courses were modified by adding HEV material to the courses. 2) The educational effectiveness and economic feasibility of the new curriculum: The new courses are offered at both the undergraduate and graduate levels. They are listed across the college in mechanical, chemical, electrical, and materials science and engineering. They are offered both on campus and to distance learning students. Students across the college of engineering and at all degree levels are integrating these courses into their degree programs. Over the three year project the course enrollments on‐campus has totaled 1,249. The distance learning enrollments has totaled 315. With such robust enrollments we absolutely expect that these courses will be in the curriculum for the long run. 3) How the project is otherwise of benefit to the public: One outcome of the project is the construction of the Michigan Tech Mobile Lab. Two complete HEV dynamometer test cells, and four work stations are installed in the 16.2 meter Mobile Laboratory and hauled by a class 8 truck. The Mobile Lab is used to teach the university courses. It is also used to deliver short courses to industry, K‐12 outreach, and public education. In 2012 the Mobile Lab participated in 22 outreach events, locally, throughout Michigan, and including events in Washington DC, Illinois, and Wisconsin. The Mobile Lab is a hit wherever it goes. In 2013 we will partner with the US Army TARDEC and be featured in their Green Warrior Convoy, a ten city tour starting in Detroit and finishing in Washington DC.

Strain Control in an Intelligent Die Based Upon Local Force Control and Blank Holder Forces

An experimental evaluation of the strains in an oval stamp forming die is presented. The die design included a flexible blank holder and active draw beads. The die was instrumented with local punch force and wrinkle sensors and control systems were developed in order to follow local punch force and wrinkle trajectories. Strains were measured after pan forming for both open and closed-loop tests. The relation between blank holder force, draw bead penetration, and strains were explored in the critical strain region of the formed pan. Closed-loop control of the local punch forces at the die ends was established using blank holder forces. The strains for tests with various lubrication conditions and draw bead penetrations were compared. It was observed that there is a tendency for the strains in critical locations to converge or remain constant for the closed-loop control tests while the strains tended to increase with blank holder force for open-loop tests. It was concluded that by controlling local punch forces, strain is indirectly controlled.Copyright

Design and Development of the 2002 Michigan Tech FutureTruck, a Parallel Hybrid Electric Vehicle

In this paper, the conversion of a production sport utility vehicle (SUV) to a hybrid electric vehicle utilizing a through-the-road parallel hybrid configuration is presented. The uniqueness of this design comes from its ability to decouple the front and rear drivetrain to simplify the packaging of underbody components. The Hybrid Theory utilizes a 2.0L, 4-cylinder engine that supplies 101 kW (135 hp) to the front wheels and a DC motor that supplies an additional 53 kW (70 hp) to the rear wheels to achieve the competition goals of a 25% improvement in fuel economy, a reduction in Green House Gas (GHG) emissions, as well as maintaining stock performance. The effects on drivability, manufacturing, fuel economy, emissions, and performance are presented along with the design, selection, and implementation of all of the vehicle conversion components. The result is a simple, low-cost option that increases the environmental friendliness that customers expect without compromising the performance they demand.

Effects of design parameters on geared two-link mechanisms

Abstract The design of a specialized agricultural harvesting machine required the use of a path generation mechanism that was compact, accurate, inexpensive to manufacture and difficult attempts involved the use of a cam and follower, but they were expensive to manufacture and difficult to operate. This paper discusses an alternative method of using a coupled, open loop, two-link mechanism to generate a polygon-like closed path (pseudo-polygon) with an integer number of curved sides and apexes. A complete development of the path and path curvaturei equations are presented. The influence of the design variables on the coupler shape (flatness of each side) is shown in equation and design chart form. An example of a successful application of this design method applied to a plant cutting mechanism is presented.