Shape memory materials undergo temperature-induced martensitic phase transformations that involve reversible dimensional changes. In performing these changes in shape, the shape-memory material is able to do work against external constraints, and this is the basis for shape-memory low-temperature heat engines. The transformation temperatures on heating and cooling are often not very different (little hysteresis) and are well defined and reproducible. Furthermore, these temperatures can be adjusted by varying the composition of the shape memory alloy. Internal combustion engines dissipate approximately two-thirds of the fuel energy as heat to the exhaust and coolant systems. A low-temperature heat engine could convert a fraction of this heat energy to useful work. This paper discusses the conceptual basis for the application of shape memory heat engines to internal combustion engine powered vehicles. Metallurgical and thermodynamic factors are discussed, as well as engine efficiency.
The paper describes recent developments in the use of stainless steel to make the parts of buses which are most liable to corrosion. Sheet metal is used for the outer panelling, and square and rectangular tubes for the body. The types of steel used and their fabrication are analyzed. Finally, a brief description is given of the stainless steels used to make car exhaust systems.
The replacement with plastic of an important component, formerly in steel, in the timing drive of a heavily duty diesel engine has been studied and realized. The substituted part is the toothed coupling connecting the injection pump to the timing drive. Torque that stresses the coupling has been measured with laboratory tests. The tooth stresses have been calculated with FEM analysis. Finally, fatigue tests have been carried out directly on the engine at different loadings. The test results are consistent with the predicted behavior of this component.
As a result of a phase transformation, shape memory alloys can change their shape when the temperature changes. This unusual effect can be utilized in actuation and fastening components for automotive applications. Springs made from Ni-Ti shape memory alloys change their rate in a predetermined temperature range due to a significant change in the elastic modules of the material. They can be used as sensor-actuators in pressures control valves or oil cooler by-pass valves in automatic transmissions or to compensate for oil viscosity changes in shock absorbers or thermal expansion of dissimilar materials in gear boxes. If the recovery is constrained, i.e., shape memory element is physically prevented from returning into its original shape, a potentially high stress is generated. This effect is used in fastener rings. Fasteners made from Ni-Ti alloys provide high reliability and easy installation for braid terminations, locating of shaft mounted components, connectors and hose clamps.
The trend toward lighter vehicles for improved performance has recently introduced the use of aluminum and plastic materials for vehicle bodies and drive trains. In particular, the aluminum alloy block foar engine application is certain to reappear. The soft aluminum cylinder liner will require additional treatment before acceptance. Three possible approaches appear to solve the aluminum cylinder liner dilemma. These approaches are: 1) use of high silicon aluminum such as the 390 aluminum; 2) insert or cast steel liners into the aluminum engine block; and 3) ceramic coat the low cost standard aluminum engine block. Each has known advantages and disadvantages. It is the purpose of this paper to present the merits of option 3, the ceramic coated aluminum cylinder bore, from the standpoint of low weight, cost, and tribological effectiveness. The advantages of approaches 1) and 2) are obvious. High temperature after treatment of the ceramic engine components is not required.
There is a strong interest around the world in natural gas as an alternative fuel. This paper is concerned with the option of converting diesel engines to spark ignition operation. Although this may appear to be an outrageous thermodynamic action, it is preferable to using natural gas in a low compression gasoline engine conversion. An investigation is described in which engine maps were produced for a 5.6 litre direct injection diesel engine converted to CNG. The diesel operating characteristics have been compared with those of the spark ignition conversion at compression ratios of 18:1 (the original diesel value), 15:1 and 13:1. Detailed data are presented for the 15:1 compression ratio. These test results are supplemented by results for other diesel conversions. The use of these engines in bus fleet operations is also discussed.
Predictable and unpredictable forces will change the direction of the charge-air systems industry. The driver of diesel engine development will be the stringent emissions regulations of the 1990s. The drivers in the gasoline engine market will be improved fuel economy, performance, durability and emissions. Forces will also influence the charge-air marketplace, including changes in emission standards, national fiscal policies, political issues, fuel prices, alternate fuels and consumer tastes. The world community mandate for engines that are clean, quiet, durable and fuel efficient will be satisfied, increasingly, by first-tier component suppliers developing integrated systems solutions.
To improve the cold startability of methanol, methanol-butane mixed fuel was experimented. Engine performance and exhaust emissions are obtained with methanol-butane mixed fuel. These characteristics are compared with those of methanol and gasoline. The mixing ratios of methanol and butane are 50:50 (M50), 80:20 (M80), and 90:10 (M90) based on the calorific value. As a result, M90 produces more power than gasoline and more or less than methanol depending on the engine speed and the excess air ratio. Brake horse power of M90 is higher than that of gasoline by 5 - 10 %, and brake specific fuel consumption is smaller than that of gasoline by 17 % to the maximum based on the calorific value. NOx emission concentrations for M90 are lower than those for gasoline and higher than those for methanol because of the effect of butane, CO emission concentrations are somewhat lower than those for methanol and gasoline.
In order to achieve lean burn engine control system, it is necessary to develop high accuracy air fuel ratio control technology including transient driving condition and lean burn limit expansion technology. This paper describes the following. 1 The characteristics of the transient response of the fuel supply are clarified when various kinds of air flow measuring methods and fuel injection methods are used. 2 To achieve stable combustion in lean mixture, fine fuel droplet mixture, whose diameter is less than 40 μm, needs to be supplied.
For the purpose of satisfying today's market demands, new 8 and 11 liter diesel engines, named "STORM" series, have been developed and moved into production in 1986. Based on the predecessors which have been produced since 1975, the development of the STORM series aimed high performance, low emission, long life-time and low operating costs. In order to consult customers' convenience, exchangeability of engine parts and commonality of vehicle installations with the former engines had to be maintained. This paper describes the development work of STORM engines, and the design aspects and performance characteristics of these engines.
A procedure has been developed for evaluating equivalent drive cycle emission results from raw exhaust gas emissions data obtained from an engine under test on a computer controlled Vehicle Simulator Engine Dynamometer. The emitted species data is integrated with the air intake flow rate to determine the total mass of emissions, after correcting for the reduction in exhaust gas mass due to precipitation of the moisture of combustion. This procedure eliminates the need for the Constant Volume Sample (CVS) System attached to the vehicle exhaust while undergoing simulated drive testing on a chassis dynamometer to evaluate compliance of the test vehicle with the Australian Design Rules, ADR27 and ADR37. Sources of error with the procedure are examined by comparing the fuel consumption measured using a volumetric technique during the test with that evaluated by a carbon balance procedure as given in the Australian Design Rules.
Unsteady laminar flame propagation confined in a closed cylindrical combustion bomb is studied by numerical computation for an axisymmetric two-dimensional laminar flame. Computation includes complete two-dimensional unsteady Navier-Stokes equations of change for a chemically reacting propane-air mixture. Implicit Continuous fluid Eulerian, Arbitrary Lagrangian Eulerian finite difference technique, simplified reaction kinetics models, and artificial flame stretching transformation and inverse transformation were adopted in the calculation. Physically realistic flame behavior can be demonstrated even with rather coarse computing cell size, simplified reaction kinetics models, and personal computer level low power computing machines.
Statistical Energy Analysis (SEA) method is used to predict Sound Transmission Loss (STL) of sound barrier assemblies (SBA) commonly used in automotive dashmat design. Tests are performed for dashmat plaques with and without design features, and SEA equations have been used for predicting transmission loss with acceptable accuracy below the interception (cavity resonance) frequency. For frequency range higher than interception point, the SEA software used overestimates STL. For dashmat tests with design features, test results and SEA predictions are generally agreeable.
In Statistical Energy Analysis and Energy Flow Analysis models of connected beam systems, it is necessary to determine the power reflection and transmission coefficients of the structural joints. The use of a spectral element formulation to estimate the joint coefficients for any number of rigidly connected beams oriented at any angle in all three dimensions is presented. The longitudinal, transverse, and torsional wave types are modeled and assembled into beam elements. A force is applied to the system and the magnitudes of the transmitted and reflected waves are identified and used to calculate the joint's power reflection and transmission coefficients. Examples are presented to illustrate the procedure.