Search Results

Conventional HVAC systems adjust the position of a temperature door, to achieve a required air temperature discharged into the passenger compartment. Such systems are based upon the fact that a conventional (non-hybrid) vehicle's engine coolant temperature is controlled to a somewhat constant temperature, using an engine thermostat. Coolant flow rate through the cabin heater core varies as the engine speed changes. EREVs (Extended Range Electric Vehicles) & PHEVs (Plug-In Hybrid Electric Vehicles) have two key vehicle requirements: maximize EV (Electric Vehicle) range and maximize fuel economy when the engine is operating. In EV mode, there is no engine heat rejection and battery pack energy is consumed in order to provide heat to the passenger compartment, for windshield defrost/defog and occupant comfort. Energy consumption for cabin heating must be optimized, if one is to optimize vehicle EV range.

Coolant pipes are a prime connection units present in any engines that facilitates the flow of coolant and thereby keeping the engine under its optimum operating condition. Among the several influencing factors that deteriorate engines performance, the coolant leak is also one of the contributors. This could be caused primly due to leakage issues that arises from the pipe press fit zones. Henceforth it is very important to understand the root cause of this press-fit connection failure. The present study deals with press-fit between the pipe and housing in an engine which is subjected to extreme thermal loads (min of -40°C to a max temperature of +150°C) thereby causing the press-fit loosening effect.

Organic acid degradation products and other anions in engine oil were speciated by capillary electrophoresis (CE) and liquid chromatography-mass spectrometry (LCMS) with electrospray ionization. The sample preparation procedure involved selectively extracting the acids and other water soluble salts into 0.05M aqueous potassium hydroxide. Samples of engine-aged mineral oil and synthetic engine oil contained formic acid, acetic acid, and complex mixtures of fatty acid degradation products. CE analysis of formic acid, acetic acid and selected fatty acids is proposed as a new chemical analysis method for evaluating the condition of engine oil and for studying the effects of high temperature-high load (HTHL) oxidation. Because the overall pattern of CE peaks in the electropherogram changes with oil age or condition, CE-fingerprint (i.e., pattern recognition) techniques may also be useful for evaluating an aged oil's condition or remaining service life.

Aeration properties of lubricants is an increasing concern as the design of powertrain components, specifically transmissions, continue to become more compact leading to smaller sumps and higher pressure requirements. Although good design practices are the most important factors in mitigating the aeration level of the fluid, the fluid properties themselves are also a contributing factor. This paper investigates the aeration properties of specific base oils commonly used to formulate modern transmission fluids using the General Motors Company Aeration Bench Test found in GMN10060. The test matrix includes thirteen different fluids representing a cross-section of base oil types, manufacturers, and viscosity grades. Per the procedure found in GMN10060, the bench test measures the aeration time, de-aeration time, and percent maximum aeration of the fluid at three temperatures, 60°C, 90°C, and 120°C. In the end, the results are compared with four commercially available transmission fluids.

This paper investigates changes in fuel economy of a mid-size sedan at various engine cooling fan power levels and front grille opening areas. A full vehicle model was built using MATLAB Simulink to calculate the fuel economy (MPG). The model utilized inputs from aerodynamic wind tunnel testing as well as FTP and MVEG dynamometer tests results. Simulation and testing was carried out at three front opening areas and three engine cooling fan power levels. The results provide a guideline for optimizing the front grille opening vs. engine cooling fan power combination at various driving conditions.

A comprehensive experimental and theoretical approach was undertaken to understand the phenomenon of pre-ignition and to assess parameters to improve or even eliminate it completely. Oil mixing with fuel was identified as the leading theory of self ignition of the fuel. End of compression temperature has to meet a minimum level for pre-ignition to take place. In this work a comprehensive list of parameters were identified that have a direct and crucial role in the onset of pre-ignition including liner wetting, injection targeting, stratification, mixture motion and oil formulation. Many secondary effects were identified including ring dynamics, ring tension, spark plug electrode temperature and coolant temperature. CFD has been extensively used to understand test results including wall film, A/F ratio distribution and temperature at the end of compression when looked at in the context of fuel evaporation and mixing.

Small electric DC (Direct Current) motors used to actuate various mechanisms in vehicles have failed prematurely when exposed to some formulations of lubricants, which leached into the motor and caused shorting. The subject study explored this failure mechanism in detail as evidenced in vehicle power door lock actuators. Experiments were conducted through the application of various types of lubricants to motors in varying ways to re-create the failure mode experienced by the authors, and to determine an optimized selection of lubricant for maximized cycle life, robust to inherent component manufacturing process variation in both the amount and location of lubrication placement. The detailed data, photographs and conclusions which resulted were summarized. The electric motor failure mode experienced in the example situation was first explained and illustrated with detailed photography.

This paper describes the rationale for the technology selection and speed control methods for electric cooling fans used for typical automotive applications, including most passenger cars and even some light duty truck s. Previous selection criteria were based primarily around cost, simplicity of implementation and reliability. However, the more recent focus toward fuel economy and optimization of energy consumption at a vehicle level has given a greater priority to the minimization of electrical power draw. Specifically, that need is addressed through both efficiency of the electric motor at any operating condition as well as providing a control method that delivers only the minimum electrical power to meet engine cooling and air conditioning requirements. This paper will explore the various control methods available, their relative merits and shortcomings and how they influence both FTP and real world fuel economy.

Typical seal immersion testing in lubricants does not aerate the lubricant as typically seen during normal operation of a transmission or axle. This paper will discuss a new test apparatus that introduces air into transmission fluids and gear oils during seal immersion testing. The seal materials selected for the testing are from current vehicle applications from several different material families. The test results compare the standard properties: change in tensile strength, elongation, hardness, and volume swell. Several tests were completed to investigate and refine the new testing method for seal compatibility testing with transmission fluids and gear oils. Initial results from the first data sets indicate that lubricant aeration helps improve test repeatability. In addition to aeration, the test results explore appropriate fluid immersion temperature for repeatability and appropriate test duration.

In recent years, there has been a sustained effort by the automotive OEMs and suppliers to improve the vehicle driveline efficiency. This has been in response to customer demands for greater vehicle fuel economy and increasingly stringent government regulations. The automotive rear axle is one of the major sources of power loss in the driveline, and hence represents an area where power loss improvements can have a significant impact on overall vehicle fuel economy. Both the friction induced mechanical losses and the spin losses vary significantly with the operating temperature of the lubricant. Also, the preloads in the bearings can vary due to temperature fluctuations. The temperatures of the lubricant, the gear tooth contacting surfaces, and the bearing contact surfaces are critical to the overall axle performance in terms of power losses, fatigue life, and wear.

This paper describes rationale for determining the apportionment of variable or ‘shuttered’ airflow and non-variable or static airflow through openings in the front of a vehicle as needed for vehicle cooling. Variable airflow can be achieved by means of a shutter system, which throttles airflow through the front end and into the Condenser, Radiator, and Fan Module, (CRFM). Shutters originated early in the history of the auto industry and acted as a thermostat [1]. They controlled airflow as opposed to coolant flow through the radiator. Two benefits that are realized today are aerodynamic and thermal gains, achieved by restricting unneeded cooling airflow. Other benefits exist and justify the use of shutters; however, there are also difficulties in both execution and practical use. This paper will focus on optimizing system performance and execution in terms of the two benefits of reduced aerodynamic drag and reduced mechanical drag through thermal control.