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Valeo Climate control is developing a software package for the design and simulation of car air-conditioning systems. This software package aims to improve Valeo's response to customer requirements concerning delays for design and sizing car air-conditioning systems performances and cost reduction. Further it shall help to capitalize our competence and expertise on the A/C systems. The comparisons between simulation and tests give a good level of accuracy. The software consists of three modules: A first module for car cabin thermal simulation in dynamic and stationary conditions. A second module for the determination and optimization of the A/C system components. A third module is under development for the dynamic simulation of the A/C system in non-standard operating conditions.

Automotive interiors are undergoing rapid transformation with the introduction of invisible PSIR integral systems. This styling trend requires continuous class A surface for the Instrument Panel (IP) and introduces complexities in the design and analysis of PSIR integral systems. The most important criterion for airbag doors is that it must open as intended, at the tearseam, within the deployment temperature range and without fragmentation. Consequently it is imperative that in analytical simulations, the finite element model of the tearseam is accurate. The accuracy of the model is governed by (a) optimal level of refinement, (b) surface geometry representation and (c) material model. This paper discusses modeling methodology for tearseams with respect to mesh refinement and the effect of geometry.

This paper presents the results of a study into an innovative system using a new type of technology for the automotive domain with the aim of improving passengers' thermal comfort. A study of the thermal interactions between the cabin and its passengers shows that radiative heat transfers clearly contribute to the passengers' thermal discomfort during the first few minutes of a vehicle's use. Therefore, to limit this kind of heat exchange, an innovative A/C system combining a conventional automotive A/C loop and a Heat Pipe Dashboard Panel has been developed. This reduces the dashboard temperature rapidly, immediately after starting the A/C system (70°C to 10°C in 3 min).

As the global auto industry wrote the final chapter on its first century, we saw the average thickness of an automotive instrument panel drop from 3.0 mm-3.5 mm to 2.0 mm-2.3 mm, as found in the 1999 Volkswagen Jetta and Golf. By reducing the wall thickness of the instrument panel, Volkswagen started an industry trend: both OEMs and tiers are investigating technologies to produce parts that combine a lower cost-per-part via material optimization and cycle-time reduction with the superior performance of engineering thermoplastics. The goal is to produce parts that are positioned more competitively at every stage of the development cycle - from design, to manufacturing, to assembly, to “curb appeal” on the showroom floor. The key to this manufacturing and design “sweet spot” is a technology called thinwall - the molding of plastic parts from engineering thermoplastics with wall thicknesses thinner than conventional parts of similar geometry.

As the need for plastic components with high-performance and low systems cost continues to escalate, the issues associated with bringing applications to automotive market have become more complex. Automotive applications such as seamless integral Passive Supplemental Inflatable Restraint (PSIR) systems can have tearseams that are either molded-in or laser scored. Molded-in tearseams in seamless Instrument Panels (IP) eliminate the secondary operation of laser scoring, but they warrant thin wall molding conditions. This paper describes material characterization under thinwall molding conditions wherein the effects of processing on mechanical properties are explored. This paper also discusses results from a proprietary finite element code developed at GE to predict the processing parameters, which affect the mechanical properties of the material at the tearseam in a seamless IP system.

In order to reduce the fuel overconsumption, new air conditioning systems fitted with externally controlled compressors have been implemented. Their operating principle consists in driving electrically (external control) the compressor displacement in order to adjust the cooling capacity delivered by the A/C system to the cooling capacity required by the passenger compartment. Therefore, it is possible to reduce the mechanical power absorbed by the compressor and by this means, the fuel overconsumption. However, this potential of fuel consumption reduction can be only achieved under the condition that the other components of the A/C system, such as the thermostatic expansion valve (TxV), are well adapted all together in order to fully take advantage of the implementation of such new type of compressors. The paper describes the different possibilities of optimization of the TxV in regard to hunting phenomena.

OEM and Tier One integrated suppliers are in constant search of cockpit system components that reduce the overall number of breaks across smooth surfaces. Traditionally, soft instrument panels with seamless airbag systems have required a separate airbag door and a tether or steel hinge mechanism to secure the door during a deployment. In addition, a scoring operation is necessary to ensure predictable, repeatable deployment characteristics. The purpose of this paper is to demonstrate the development and performance of a cost-effective soft instrument panel with a seamless airbag door that results in a reduced number of parts and a highly efficient manufacturing process. Because of the unique characteristics of this material, a cost-effective, lightweight solution to meet both styling requirements, as well as safety and performance criteria, can be attained.

Electrical Air Conditioning Systems for 42 V vehicles will provide many benefits in terms of Environment protection, car Architecture, cabin Comfort and overall Safety. E-A/C Systems essentially differ from conventional ones by the use of electrical compressors. First of all, they will be particularly well adapted to new powertrains, helping to make them more environmentally friendly. Accurate control and high efficiency under the most common thermal conditions will reduce the A/C impact on fuel consumption. Besides, higher sealing integrity will cut emissions of refrigerant during normal operation and maintenance. Secondly, the use of an electrically driven compressor (EDC) will suppress a belt, and will reduce the packaging constraints. This will help to design new vehicle architectures. Thirdly, the electrification of air conditioning will allow better thermal comfort. In particular, E-A/C Systems provide a good opportunity for cabin pre-conditioning.

Automotive styling and performance trends continue to challenge engineers to develop cost effective bumper systems that can provide efficient energy absorption and also fit within reduced package spaces. Through a combination of material properties and design, injection-molded engineering thermoplastic (ETP) energy absorption systems using polycarbonate/polybutylene terephthalate (PC/PBT) alloys have been shown to promote faster loading and superior energy absorption efficiency than conventional foam systems. This allows the ETP system to provide the required impact protection within a smaller package space. In order to make optimal use of this efficiency, the reinforcing beam and energy absorber (EA) must be considered together as an energy management system. This paper describes the development of a predictive tool created to simplify and shorten the process of engineering efficient and cost effective beam/EA energy management systems.

The history behind Polymer Class “A” Body Panels for automotive applications is very interesting. The driving factors behind these applications have not changed significantly over the past sixty years. Foremost among these factors is the need for corrosion and dent resistance. Beginning with Saturn in 1990, interest in polymer body panels grew and continues to grow up to the present day, with every new global application. Today, consumers and economic factors drive the industry trend towards plastic body panels. These include increased customization and fuel economy on the consumer side. Economic factors such as lower unit build quantities, reduced vehicle mass, investment cost, and tooling lead times influence material choice for industry. The highest possible performance, and fuel economy, at the lowest price have always been a goal.

The arising “Stop&Go” function contributes to the reduction of new cars fuel consumption. However, as the engine shuts off when the car stops, cabin heating and air conditioning cut off because they are belt driven. This paper first describes the cabin temperature evolution when it occurs. It shows that solutions must be found in order to guarantee passenger comfort maintaining. Different concepts are presented, built on fuel, electrical or thermal energy storage. A comparison is provided, showing that the latter should be preferred. The biggest remaining issue for long stops is storage itself.

Reduction of internal combustion engines fuel consumption is permanently researched. It leads automotive companies towards global energetic simulation tools to describe the interactions between the engine and the energy consumer systems. Valeo with the EMN Department of Energetic, develop a vehicle energy management tool. It will be able to describe the interactions between: engine, the car cabin heating system, electrical systems and other energy consumers (additional heating system, air conditioning system) implied in the vehicle operation. The first results given by the simulation model have approached quite accurately, the coolant loop warm-up curve, measured during a vehicle test in wind tunnel. The model solves the energy balance on the oil and coolant loops and computes: the heat flux from engine to coolant, the distribution of coolant flows in branches, the thermal exchanges involved in the heater core, the cooling radiator and the oil cooler.

Experiments were conducted on laminate evaporator to determine the effect of the tank position on the evaporator heat transfer and pressure drop. The experiments were conducted on the evaporator calorimeter facility that is fully instrumented per ASHRAE specifications. A typical 4 pass laminate evaporator was used for testing. The refrigerant used for this investigation was R-134a. An oil circulation ratio of 2% was used for this study. The test conditions were: air inlet state was maintained at 27°C of dry bulb temp and 50% RH; average condensing and evaporation pressures were maintained at 15.5 & 1.96 kg/cm2 G, respectively with 5°C evaporator superheat and 5°C condenser subcooling; and air flow rate was varied from 120 to 480 m3/hr. The result shows that there is a significant impact of the tank position on the evaporator heat transfer rate and pressure drop.

This paper presents the results of a study of the various thermal interactions between the automotive passenger compartment and the passengers, using the equivalent temperature concept. Radiative and convective heat exchanges are described. A technical proposal to improve the thermal comfort of passengers is also made.

Expanding the temporal scope of air conditioning in cars is an important customer expectation. It must be available when the engine is off for climate control purposes (during “stop&start” operations or short parking) or for thermal comfort preparation (cabin pre-cooling). Different technical solutions can be classified according to the kind of energy storage they are based on. Regarding stop&start, many solutions are possible. The selection should be made in accordance with the hybridisation level of the vehicle. For parking cooling and pre-cooling, weight is the main issue. Thermal storage or electrical batteries can be used, but tens of kilograms are required. Auxiliary power units would be necessary to obtain full comfort in these conditions.

The automotive industry is continually striving for opportunities to take additional cost and mass out of vehicle systems. Large parts such as an Instrument Panel retainer are good candidates because a small percent reduction in mass can translate into a significant material mass savings. Multiple requirements for a soft instrument panel including safety, stiffness, adhesion, etc. can make these savings difficult to achieve. This paper will describe how a new material and process development for the fabrication of a soft instrument panel can produce 50% weight savings with a 20% cost reduction potential. In addition, this new technology exhibits improved performance over existing materials during safety testing.

The paper deals with an innovative system using a new type of technology for the automotive domain in order to improve rear passengers’ thermal comfort. This device is an add-on thermal module plugged into the headliner of a car. This kind of product has been developed and integrated in a car for validation. Tests have been performed in terms of thermal comfort improvement using a human panel. They show a real effect at the head level of the rear passengers in summer and in winter. Moreover, it offers independent control to the left and right rear passengers in terms of mass flow and temperature with easier in-vehicle integration for the car makers than a rear HVAC.

The thermochemical energy storage could be a suitable solution for heating and air conditioning electric vehicles. This paper gives the results of a preliminary study engaged to test the STELF process using the metallic chloride/ammonia couple. Among the large number of solid/gas couples available, the MnCl2/NH3 couple features an energy storage capacity of about 180 Wh and 90 Wh per kg of reactive and answers to an automotive application temperature respectively for the heating and the cooling. In winter, the reactor can provide heating to warm the passenger compartment but also to the outer evaporator heat exchanger to avoid the icing up phenomenon. Simulations show the thermodynamic feasibility of the process in the heating, cooling and regeneration modes in order to warm up, air condition and preheat respectively the electric car passenger compartment.

The paper presents the VALEO and RENAULT approach to study odor problems for passengers compartment. The first part describes the method chosen to form a panel, and the second part presents a vehicle application.

The instrument panel (IP) is one of the largest, most complex, and visible components of the vehicle interior, and like most other major systems in passenger cars and light trucks, it has undergone considerable aesthetic and functional changes over the past decade. This is because a number of design, engineering, and manufacturing trends have been driving modifications in both the role of these systems and the materials used to construct them since the mid- '80s. This paper will trace the recent evolution of IP systems in terms of the trends affecting both design and materials usage. Specific commercial examples will be used to illustrate these changes.