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Technical Paper

Gear Whine Reduction for a New Automatic Transmission

2001-04-30
2001-01-1506
Gear whine in 1st and 2nd gears in a new rear wheel drive automatic transmission was identified as a potential customer dis-satisfier. Improvements to the vehicle system were implemented, but did not sufficiently reduce the noise. CAE modeling and hardware testing were used for gear tooth optimization, transmission system, driveline, and vehicle system studies. The planetary gears were re-designed with increased contact ratio, and significant interior noise reduction was achieved; but some vehicles still had excessive noise due to gear parameter variability from multiple sources. Using a DOE and statistical studies, a set of gear parameter targets were identified within the tolerances of the design, which achieved the program objectives for noise.
Technical Paper

Gear Whine Improvements for an Automatic Transmission through Design Retargeting and Manufacturing Variability Reduction

2001-04-30
2001-01-1505
Gear whine in 1st gear for an automatic transmission that has been in production for nearly thirty years was identified as an NVH issue. Due to advances in vehicle level refinement, and reduction of other masking noises, the automatic transmission gear whine became an issue with the customer. Since the transmission was already in production, the improvements had to be within the boundaries of manufacturing feasibility with existing equipment to avoid costly and time consuming investment in new machines. The approach used was one of identifying optimum values of existing gear parameters to provide a reduction in passenger compartment noise. The problem was in a light truck application. Objective noise measurements were recorded for 10 transmissions from more than 50 driven in vehicles. The transmissions were disassembled and the gears inspected.
Technical Paper

Comparison of Performance between Several Vehicle Windshield Defrosting and Demisting Mechanisms

2001-03-05
2001-01-0582
The safety and comfort aspects of passenger cars are significant sales argument and have become a topic of rising importance during the development process of a new car. The objective of this study is to compare the performance of several current model vehicles, highlight the drawbacks of current defrosting/demisting systems and point the way to improved passive mechanisms. The investigation is experimental. The experiments are carried out using full-scale current vehicle models. The results show that the current designs of the defroster nozzle give maximum airflow rates in the vicinity of the lower part of the windshield, which decrease gradually towards the upper parts of the windshield. This hinders and limits the vision of the driver, particularly at the top of the windshield, which can be uncomfortable and indeed dangerous.
Technical Paper

Finite Element Vibration Studies of As-Installed Power Steering Pumps

2003-05-05
2003-01-1671
Pump whine as well as other NVH issues related to power steering system can become customer concerns at the vehicle level. In order to avoid that, proposed treatment of the pump structure and its installation on the engine should be performed. This is particularly important because most vane pumps have a wide range of excitation that can reach 1000 Hz (30th order @ 6000 rpm). This requires maximizing the ‘as installed’ frequencies of the pump to avoid coincidence with the engine and other FEAD harmonics.
Technical Paper

Bending Fatigue Behavior of Carburized Gear Steels: Four-Point Bend Test Development and Evaluation

1996-02-01
960977
The ability to evaluate the bending fatigue behavior of carburized low alloy steels in a laboratory and relate these measurements to performance of high contact ratio helical gears is important to the design and development of transmissions. Typical methods of evaluating bending fatigue performance of carburized gear steels do not directly represent helical planetary gears because they lack the geometric and loading conditions of planetary pinions. The purpose of this study is twofold; 1) development of a lab fatigue test to represent the fatigue performance of planetary pinion gears tested in a dynamometer and 2) evaluation of the influence of alloy content on bending fatigue performance of two steel alloys. The steels under evaluation were modified 8620M and 4615M alloys machined into bend bars with a notch representing a gear root and carburized to a case depth of approximately 0.35 mm (using the same carburizing cycle as the planetary pinion gears).
Technical Paper

Bending Fatigue Behavior of Carburized Gear Steels: Planetary Gear Test Development and Evaluation

1996-02-01
960978
Little information is available concerning the bending fatigue behavior of helical gears with tall thin teeth and high contact ratios, particularly for planetary pinions which are subjected to fully reversed loading. The most common methods to acquire gear bending fatigue data are either through a four-square recirculating power arrangement or unidirectional single tooth bending experiments on standardized spur gears. There are some advantages to these test methods, but they generally do not represent actual operating conditions of a planetary gear environment. The purpose of this study was to develop a bending fatigue test for planetary pinions in automatic transmissions which would better represent actual operating conditions. The new testing procedure was used to evaluate the bending fatigue behavior of three gear steel/processing combinations. The results from the planetary gear testing is compared with laboratory four-point bending experiments.
Technical Paper

A New Transient Passenger Thermal Comfort Model

1997-02-24
970528
This paper presents a new transient passenger thermal comfort model. The model uses as inputs the vehicle environmental variables: air temperature, air velocity, relative humidity and mean radiant temperature all of which can vary as a function of time and space. The model also uses as inputs the clothing level and the initial physiological state of the body. The model then predicts as a function of time the physiological state of the body and an effective human thermal sensation response (e.g. cold, comfort, hot, etc.). The advantage of this model is that it can accurately predict the human thermal sensation response during transient vehicle warm-up and cooldown conditions. It also allows design engineers the ability to conduct parametric studies of climate control systems before hardware is available. Here we present the basis of the new thermal comfort model and its predictions for transient warm-up and cooldown conditions.
Technical Paper

Measurements of the Effect of In-Cylinder Motion on Flame Development and Cycle-to-Cycle Variations Using an Ionization Probe Head Gasket

1997-02-24
970507
An ionization probe head gasket (to IPHG) was used to investigate flame development in a 2.0L I4 engine with two in-cylinder fluid motions. A new technique was developed to display accurate flame contours at 2%, 10% and 50% mass fraction burned crank angles using the measurements of flame arrival time from the ion probes in conjunction with cycle simulations. The flame arrival and burn rate information is used to scale the relationship between flame radius and mass fraction burned from the cycle simulation to create accurate contours of the flame for each cycle. The tumbling motion inside the combustion chamber produced by the production intake ports convected the flame towards the exhaust side of the chamber. The geometry of the flame development was relatively unaffected by changes in speed and load.
Technical Paper

Automated Production Noise Testing of Power Steering Pumps

1997-05-20
971911
This case study presents a new automated production noise test for power steering pumps. The test included adaptive noise cancellation, and a neural network implementation. The result mapped the pump acceleration signature into an objective repeatable noise metric. The test algorithm was a distributed DSP architecture designed for real-time measurement and decision processing. It was implemented with no increase in test cycle time. It accomplished the correlation of in-vehicle power steering pump noise to it's vibration characteristics, and retrofitting of accelerometers in place of microphones for acceptance testing.
Technical Paper

Modelling the Dissipative Effect of Seal Air Hole Spacing and Size on Door Closing Effort

1997-05-20
971901
Door weather strip seals are designed with ventilation holes spaced at regular intervals along the seal system to expedite the flow of air from the seal system during the door closing process. The flow of air through the ventilation holes represents a nonlinear damping mechanism which, depending upon hole size and spacing, can significantly contribute to door closing effort. In this study we develop one- and two- dimensional versions of a nonlinear damping model for seal compression load deflection (CLD) behavior which incorporate the effects of seal damping response due to air flow through the ventilation holes. The air flow/damping models are developed from first physical principles by application of the mass and momentum balance equations to a control volume of entrapped air between consecutive air ventilation holes in the seal system.
Technical Paper

Acoustic Analysis of Vehicle Ribbed Floor

1997-05-20
971945
Ribbed floor panels have been widely applied in vehicle body structures to reduce interior noise. The conventional approach to evaluate ribbed floor panel designs is to compare natural frequencies and local stiffness. However, this approach may not result in the desired outcome of the reduction in radiated noise. Designing a “quiet” floor panel requires minimizing the total radiated noise resulting from vibration of the floor panel. In this study, the objective of ribbed floor panel design is to reduce the total radiated sound power by optimizing the rib patterns. A parametric study was conducted first to understand the effects of rib design parameters such as rib height, width, orientation, and density. Next, a finite element model of a simplified body structure with ribbed floor panel was built and analyzed. The structural vibration profile was generated using MSCINastran, and integrated with the acoustic boundary element model.
Technical Paper

Experimental Assessment of Wind Noise Contributors to Interior Noise

1997-05-20
971922
Wind noise reaches the interior of a vehicle through a variety of mechanisms including: aerodynamic excitation of vibration and reradiation from the greenhouse surfaces; acoustic transmission through door seals including gaps and glass edge leaks, and due to airborne transmission of noise generated by wind interaction with body panels. This paper presents experimental results that quantify contributions to interior noise from individual greenhouse surfaces and from airborne sources on the underbody. The measurements were carried out on a production vehicle in a wind tunnel. Greenhouse surfaces, in addition to the driver window are important contributors to interior noise along with airborne transmission of noise generated due to the flow over and through the vehicle underbody.
Technical Paper

Exhaust Valve Seat Leakage

1997-05-01
971638
A 1.9L four cylinder engine was evaluated for leakage of cylinder charge through the exhaust valve seats. Fast FID HC analyzer traces reveal leakage. Static leakdown tests do not correlate with the Fast FID measurement, unlike previously published reports for a different engine. The causes of exhaust valve seat leakage are likely to be Flakes of cylinder deposits lodging in the valve seat Valve seat distortion due to the thermal and pressure loading of the cylinder head structure Because deposit related effects are very history dependent, it is very difficult to obtain quantitative results. Some experimental observations: Static pressure leakage measurements show variation of leakage area with cylinder pressure, caused by flexing of the valve head. Dynamic leakage results are history dependent. Leakage is reduced after running at high speed/load, and gradually build up during extended light load low speed operation.
Technical Paper

Vacuum EGR Valve Actuator Model

1998-05-04
981438
As part of a general EGR system model, an adiabatic thermodynamic vacuum EGR valve actuator model was developed and validated. The long term goal of the work is improved system operation by correctly specifying and allocating EGR system component requirements.
Technical Paper

Powertrain Applications for Rapid Prototyping, Fabrication and Tooling in Motorsports

1998-11-16
983091
Rapid Prototyping, Fabrication and Tooling is a process that blends a series of technologies (machines, tools, and methods) capable of generating physical objects directly from a CAD database. The process dramatically reduces the time spent during product development by allowing for fast visualization, verification, iteration, optimization, and fabrication of parts and tools. Many new techniques of tooling have been and are being developed by using rapid fabricated parts. These are having a dramatic impact on both timing and costs throughout the automotive industry. One area that these methods can be utilized to their full potential is motorsports. Of particular interest is the growing use of bridge tooling to provide first article through production intent parts that promote cost effective changes.
Technical Paper

Slow Heating Process of a Heated Pintle-Type Gasoline Fuel Injector

1995-02-01
950068
The heated fuel injectors are designed to bring up fuel temperature so as to reduce HC and CO emissions during cold start. The heated injectors are similar to regular injectors except heaters are placed near the injector inlet and outlet. The heaters, which has the ability to regulate temperature at 180 °C, transform the thermal energy to heat up the liquid fuel through the injector body. The heated injectors are required to heat up fuel to the operating temperature (e.g., 120 °F or 48.9 °C) as quickly as possible and to maintain that fuel temperature for about three minutes. However, test results indicate it takes more than two minutes for the fuel temperature to reach the desired operating temperature. Objective of this work is to find out the mechanisms controlling the slow heating process through CFD analysis. The computational domain covers the whole injector, from inlet to exit, since the heaters located near the top and bottom of the injector.
Technical Paper

A Comparative Study of the Fatigue Behavior of Spot Welded and Mechanically Fastened Aluminum Joints

1995-02-01
950710
The cyclic behavior of single overlap aluminum joints joined through a number of different methods has been investigated using Alcan 5754-O, an alloy that potentially could be used in structural applications. Overlap shear tests of spot welded, clinched and riveted joints are compared on the basis of their fatigue performance. The fatigue response of the spot welded joint was the baseline to which the other fasteners were compared. Test results showed an improvement of approximately 25% for both the mechanical clinch joints and aluminum rivets in fatigue strength at 106 cycles. The most significant improvement in fatigue strength of 100% was found for the self piercing rivets at 106 cycles. The failure behavior of the various joining methods is discussed as well as the surface appearance.
Technical Paper

Effect of Regrind on SMA Copolymer Boss/Joint Performance

1995-02-01
950810
To minimize warranty costs, due to squeak and rattle from ill fitting joints, automotive OEMs are requiring increased durability of thermoplastic attachments. There are several evaluation techniques for determining thermoplastic joint durability performance such as: strip-to-drive torque, screw pull-out force, and clamp load fall-off. A thermoplastic attachment (i.e. boss) which experiences clamp load fall-off will result in a loose fitting joint and subsequently lead to squeaks and rattles. In conjunction with the boss's performance the type of captured material between the screw and the joint can also contribute significantly to the overall retention qualities of the attachment. The purpose of this paper is to evaluate: 1.) strip-to-drive ratios for thermoplastic bosses, and 2.) changes in clamp load with respect to environmental effects (i.e. thermal exposure) on thermoplastic bosses.
Technical Paper

Effect of Post Consumer Recyclate on SMA Copolymer Boss/Joint Performance

1996-02-01
960698
The use of Post Consumer Recyclate (PCR) or Post Industrial Regrind (PIR) to manufacture thermoplastic (or thermoset) automotive parts and components has significantly increased over the last 10 years. Due to this increase in use, automotive designers are continuously challenged with the question of how PCR or PIR material differ in performance from the virgin material? To compound the dilemma, automotive OEMs are requiring increased durability of thermoplastic attachments (joints), so that warranty costs associated with interior squeak and rattle (from ill-fitting joints) are minimized. To answer this question, there exist several techniques for finding thermoplastic joint durability performance. Some of them are: strip-to-drive torque ratios, screw pull-off force and clamp load fall-off. A thermoplastic attachment (i.e. boss) which experiences clamp load fall-off will lead to a loose fitting joint and subsequently result in squeaks and rattles.
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