Your Selections

General Motors Corp.
Show Only

Collections

File Formats

Content Types

Dates

Sectors

Topics

Authors

Publishers

Affiliations

Committees

Events

   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

High-Fidelity Transient Thermal Modeling of a Brake Corner

SAE International Journal of Passenger Cars - Mechanical Systems

General Motors Corp.-Nimrod Kapas, Ajith Jayasundera
  • Journal Article
  • 2016-01-1929
Published 2016-09-18 by SAE International in United States
There is an increasing interest in transient thermal simulations of automotive brake systems. This paper presents a high-fidelity CFD tool for modeling complete braking cycles including both the deceleration and acceleration phases. During braking, this model applies the frictional heat at the interface on the contacting rotor and pad surfaces. Based on the conductive heat fluxes within the surrounding parts, the solver divides the frictional heat into energy fluxes entering the solid volumes of the rotor and the pad. The convective heat transfer between the surfaces of solid parts and the cooling airflow is simulated through conjugate heat transfer, and the discrete ordinates model captures the radiative heat exchange between solid surfaces. It is found that modeling the rotor rotation using the sliding mesh approach provides more realistic results than those obtained with the Multiple Reference Frames method. Because of the significant computational requirements involved, the scope of this paper is limited to a single braking event of a brake subsystem in an environmental chamber. Corresponding dynamometer tests have also been performed to validate the…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Analysis of Contamination Protection for Brake Rotor

SAE International Journal of Passenger Cars - Mechanical Systems

General Motors Corp.-Heewook Lee
  • Journal Article
  • 2016-01-1930
Published 2016-09-18 by SAE International in United States
Contamination protection of brake rotors has been a challenge for the auto industry for a long time. As contamination of a rotor causes corrosion, and that in turn causes many issues like pulsation and excessive wear of rotors and linings, a rotor splash protection shield became a common part for most vehicles. While the rotor splash shield provides contamination protection for the brake rotor, it makes brake cooling performance worse because it blocks air reaching the brake rotor. Therefore, balancing between contamination protection and enabling brake cooling has become a key critical factor when the splash shield is designed. Although the analysis capability of brake cooling performance has become quite reliable, due to lack of technology to predict contamination patterns, the design of the splash protection shield has relied on engineering judgment and/or vehicle tests. Optimization opportunities were restricted by cost and time associated with vehicle tests. Studies were done for various ways of analyzing the contamination qualitatively and quantitatively and are presented in this paper. Combining the technology presented in this paper along with…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Composite Thermal Model for Design of Climate Control System

SAE International Journal of Passenger Cars - Mechanical Systems

General Motors Corp.-Rupesh Sonu Kakade
  • Journal Article
  • 2014-01-0687
Published 2014-04-01 by SAE International in United States
We propose a composite thermal model of the vehicle passenger compartment that can be used to predict and analyze thermal comfort of the occupants of a vehicle. Physical model is developed using heat flow in and out of the passenger compartment space, comprised of glasses, roof, seats, dashboard, etc. Use of a model under a wide variety of test conditions have shown high sensitivity of compartment air temperature to changes in the outside air temperature, solar heat load, temperature and mass flow of duct outlet air from the climate control system of a vehicle. Use of this model has subsequently reduced empiricism and extensive experimental tests for design and tuning of the automatic climate control system. Simulation of the model allowed several changes to the designs well before the prototype hardware is available. In addition to the reduced vehicle field tests and wind tunnel tests man hours and the cost associated with them, simulation of the model allowed for the greater potential benefits of increased accuracy and optimized heating and cooling of the passenger compartment…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Signal Processing for Rough Road Detection

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

General Motors Corp.-Tameem Assaf, David Mathews, Sanjeev Naik
  • Journal Article
  • 2010-01-0673
Published 2010-04-12 by SAE International in United States
Misfire diagnostics are required to detect missed combustion events which may cause an increase in emissions and a reduction in performance and fuel economy. If the misfire detection system is based on crankshaft speed measurement, driveline torque variations due to rough road can hinder the diagnosis of misfire. A common method of rough road detection uses the ABS (Anti-Lock Braking System) module to process wheel speed sensor data. This leads to multiple integration issues including complexities in interacting with multiple suppliers, inapplicability in certain markets and lower reliability of wheel speed sensors.This paper describes novel rough road detection concepts based on signal processing and statistical analysis without using wheel speed sensors. These include engine crankshaft and Transmission Output Speed (TOS) sensing information. Algorithms that combine adaptive signal processing and specific statistical analysis of this information are presented. Vehicle test results are shown to demonstrate the efficacy of these techniques to distinguish between rough road, smooth road, and misfire.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Oil Transport Analysis of a Cylinder Deactivation Engine

General Motors Corp.-Zheng Ma
Published 2010-04-12 by SAE International in United States
Engine cylinder deactivation is used to save engine pumping loss but raises oil consumption concerns for the deactivated cylinders. In this paper, general mechanisms of oil transport via piston rings are reviewed. The characteristic of oil transport and oil accumulation in a cylinder deactivation mode through the piston ring path are analyzed. Suggestions to reduce the oil transport to the combustion chamber in a deactivated cylinder are discussed. In a deactivated cylinder, the amount of oil brought into the combustion chamber by the top ring up-scraping due to the ring/bore conformability difference between intake stroke and compression stroke is much less compared to a firing cylinder. However, compared to a firing cylinder, a deactivated cylinder has more oil entering the combustion chamber through the top ring end gap and ring groove as a result of the lower cylinder gas pressure, lower ring temperature and more frequent top ring axial movements. Suggestions are given to reduce the net upward oil transport in a deactivated cylinder, including reducing the ring/groove clearances and the sizes of the ring…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

General Motors Small Front Wheel Drive Six speed Automatic Transmission Family

General Motors Corp.-Tejinder Singh, Richard Olenzek
Published 2010-04-12 by SAE International in United States
General Motors introduced a family of small front wheel drive six speed automatic transmissions for the 2008 model year. The family currently has two variants: 6T40 and 6T45, which cover a range of vehicles from small & compact cars to small SUVs and handle engines torque capacities up to 240 Nm Gas(280 Nm Diesel) & 315 Nm Gas (380 Nm Diesel) respectively. The 6T40/45 transmissions replace GM traditional four speed automatic wrap around transmissions 4T40/45. The wrap around transmissions have Torque Converter, Pump & Controls on the engine axis and the rest of the transmission content on the output axis. The 6T40/45 have an on-axis architecture with majority of the transmission content on the engine axis and final drive & differential on the output axis. The 4T40/45 have input chain transfer whereas the 6T40/45 have an output chain transfer. The objectives behind the creation of the 6T40/45 transmissions were improved fuel economy, performance, mass and NVH as compared to the transmissions they replaced. Packaging in the existing vehicle architectures and high mileage dependability were givens.…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Effect of Simulated Material Properties and Residual Stresses on High Cycle Fatigue Prediction in a Compacted Graphite Iron Engine Block

General Motors Corp.-Brian McClory, Wai Nguyen
Magma Foundry Technologies Inc.-Christof Heisser
Published 2010-04-12 by SAE International in United States
Casting, machining and structural simulations were completed on a V8 engine block made in Compacted Graphite Iron (CGI) for use in a racing application. The casting and machining simulations generated maps of predicted tensile strength and residual stress in the block. These strength and stress maps were exported to a finite element structural model of the machined part. Assembly and operating loads were applied, and stresses due to these loads were determined. High cycle fatigue analysis was completed, and three sets of safety factors were calculated using the following conditions: uniform properties and no residual stress, predicted properties and no residual stress, and predicted properties plus residual stress.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Diagnosis of Off-Brake Performance Issues with Low Range Pressure Distribution Sensors

General Motors Corp.-David B. Antanaitis
Published 2010-04-12 by SAE International in United States
Brake caliper and corner behavior in the off-brake condition can lead, at times, to brake system performance issues such as residual drag (and related issues such as pulsation, judder, and loss of fuel economy), and caliper pryback during aggressive driving maneuvers. The dynamics in the brake corner can be strikingly complex, with numerous friction interfaces, rubber component and grease dynamics, deflections of multiple components, and significant dependence on usage conditions. Displacements of moving parts are usually small, and the residual forces in the caliper interfaces involved are also small in comparison with other forces acting on the same components, making direct observation very difficult. The present work attempts to illuminate off-brake behavior in two different conditions - residual drag and pryback - through the use of low-range pressure distribution sensors placed in between the caliper (pistons and fingers) and the brake pad pressure plates. Data from multiple sources, including dynamometer, straight-line in-vehicle, and hard cornering are presented and methods of analysis are discussed.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Improvement on Cylinder-to-Cylinder Variation Using a Cylinder Balancing Control Strategy in Gasoline HCCI Engines

General Motors Corp.-Man-Feng Chang
Propulsion Systems Research Labs, GM R&D-Hanho Yun, Jun-Mo Kang, Paul Najt
Published 2010-04-12 by SAE International in United States
Homogenous Charge Compression Ignition (HCCI) combustion offers significant efficiency improvements compared to conventional gasoline engines. However, due to the nature of HCCI combustion, traditional HCCI engines show some degree of sensitivity to in-cylinder thermal conditions; thus higher cylinder-to-cylinder variation was observed especially at low load and high load operating conditions due to different injector characteristics, different amount of reforming as well as non-uniform EGR distribution. To address these issues, a cylinder balancing control strategy was developed for a multi-cylinder engine. In particular, the cylinder balancing control strategy balances CA50 and AF ratio at high load and low load conditions, respectively. Combustion noise was significantly reduced at high load while combustion stability was improved at low load with the cylinder balancing control.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Friction Damped Disc Brake Rotor

General Motors Corp.-Omar Dessouki, Brent Lowe, Mark Riefe
Published 2010-04-12 by SAE International in United States
Over the last five years, the automotive industry has experienced a trend towards niche performance vehicles equipped with high-output powertrains. These high performance vehicles also demand higher output braking systems. One method used to provide enhanced pedal feel and fade performance is to equip vehicles with higher apparent friction linings. The challenge then becomes how to design and manufacture these brake systems without high-frequency disc brake squeal and without paying a significant mass penalty. One alternative is to design disc brake rotors with increased damping. There are several options for increasing rotor damping. The classical approach is to increase the rotor's cast iron carbon content, thus increasing the internal material damping of the rotor. However, this methodology provides only a small increase in rotor damping. Alternatively, the rotor damping can be increased by introducing friction, sometimes referred to as Coulomb damping. This paper describes two different rotor designs that utilize friction damping. Prototypes of these rotors were manufactured and tested to validate their effectiveness in controlling brake squeal.
Annotation ability available