HONDA The Power of Dreams

Enabling efficient development of high-quality products through simulation of harsh usage environments

Honda vehicles are driven even in extremely cold climates and regions where the heat can be intense. To enable users to drive safely and with peace of mind in such places, Honda needs to make sure its vehicles will perform.
Recreating the conditions of harsh usage environments in its test facilities, Honda carries out tests to determine whether electric vehicle batteries perform as intended in their design; whether climate control systems function as intended, with the ability to maintain a comfortable environment inside the cabin; and whether expansion and contraction of plastic and metal parts will undermine the quality of the product. (Final testing takes place in the field.)
By undertaking such a diverse range of evaluations under stringent conditions, Honda endeavors to develop vehicles that users will find safe and comfortable to drive.

Battery Pack Thermal Management System Test Bench

Electric vehicles are equipped with high-capacity batteries. A battery pack thermal management system test bench is used to verify whether a battery pack will function as designed in the low-temperature environments anticipated in extremely cold regions, and in high-temperature environments anticipating intense heat.

Batteries need to work efficiently and within a certain temperature range, while keeping degradation to a minimum, to ensure sufficient functionality and safety for driving. The battery pack thermal management system test bench allows testing in conditions simulating actual driving. A battery pack and thermal management system are removed intact from the vehicle and placed in a temperature-controlled chamber that can maintain a constant temperature for long periods. A charge-discharge facility is used to apply the required power loads for driving and charging. Instead of having to fit an entire vehicle inside the chamber, this keeps the equipment compact, allowing flexible testing due, for example, to the ease of replacing parts and adding, or removing, sensors.

Using the test bench, thermal management systems are tested to ensure they cool the battery as intended in driving, charging, and parking scenarios at the higher end of the suitable temperature range (envisaging a high-temperature environment). Power loads required for actual driving and charging are applied to the battery during testing. To ensure driving and charging performance even when the battery is situated at the lower end of the suitable temperature range (envisaging a low-temperature environment), thermal management systems are tested to check they warm the battery as intended, and that they actually start up in extreme cold climates.

Thermal management system fault detection testing is also performed using this facility. This entails purposely causing a part to malfunction to see if the fault detection system picks up the malfunction.

Because it enables battery charging and discharging and thermal management system operation like in an actual vehicle, the battery pack thermal management system test bench can be used to examine and review specifications in a relatively short time frame compared to costly and lengthy testing using an actual vehicle. The ability to flexibly configure parameters of measurement conditions, too, helps to improve testing accuracy. Sometimes, the evaluation process also gives rise to additional usability and new ideas, contributing to not only higher development efficiency, but also a pathway to further technological advancement.

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All-Weather Chassis Dynamometer for Climate Control Evaluation

To provide assurances about the safety and comfort of Honda vehicles in regions across the globe, Honda uses an all-weather chassis dynamometer, or dyno, to evaluate whether climate control systems perform the functions for which they were designed even in the extremely low temperatures and intensely hot conditions they encounter.

Vehicles are driven atop a platform inside a test chamber with an environment that can be controlled to achieve the desired temperature, from low to high. Air simulating the wind of motion is directed at the vehicle through a flow contraction tunnel in front of the vehicle. The facility uses a large refrigeration unit to regulate the temperature and humidity inside the test chamber and solar simulators to recreate the light of the sun. The reason that vehicles are run on the dyno is to faithfully simulate heat caused by friction within the drivetrain. To ensure that vehicles are driven atop the rollers consistently, under identical conditions, special fixtures are affixed to the wheel nuts to hold the vehicle firmly in place.

The facility is used to evaluate climate control systems of not only vehicles with engines, including hybrid electric vehicles (HEVs), but also all-electric vehicles. All-electric vehicles use their climate control cooling system to cool the battery to enable quick charging. Climate control can also be used while charging is in progress, allowing users to remain comfortable inside the cabin. This requires compatibility between battery cooling and climate control during rapid charging. Rapid charging devices are therefore installed inside the facility for the purpose of evaluating both functions during charging.

Countries all over the world have regulations requiring that windows which freeze over during the winter months must be cleared in a certain length of time from system startup using the climate control defrosting function. One role of this facility is to determine if climate control performance will comply with those regulations. In addition to compliance with regulations, climate control is also evaluated according to a set of original Honda standards from the perspective of enhancing marketability.

When evaluating climate control performance, test dummies fitted with sensors are placed in each seat to measure parameters such as air volume, temperature, and solar radiation. Honda evaluates climate control systems using its own indicators, drawing on expertise accumulated through many years of development to determine, for example, the thresholds at which people will feel warm or cold in certain body parts. However, Honda does not rely solely on data. Personnel evaluate how it actually feels in the cabin by going inside. As heat and cold are experienced differently from region to region due to the characteristics of the people living there, allowances are incorporated into indicators depending on the target market.

Honda tests climate control performance on test courses and public roads worldwide, even examining the adaptability of climate control systems to changes in the weather and the environment that occur while driving. Use of an all-weather chassis dynamometer, however, allows Honda to do more than simply evaluate basic climate control functions, such as cooling and heating. Extensive research into the factors and reasons behind people’s comfort or discomfort has made it possible to delve deeper into control technologies for making people feel comfortable. This is because tests can be performed with consistency, unlike field tests, which are influenced by weather conditions. In the case of electric vehicles, another consideration is electricity consumption and Honda cannot be content to simply pursue functional performance. The cabin must be kept comfortable without consuming much electricity. The all-weather chassis dynamometer for climate control evaluation contributes to the development of climate control systems that strike a balance between these many different factors.

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Low-/High-Temperature Visual Marketability Test Chamber

Plastic parts like bumpers and garnishes expand as they heat up when exposed to solar rays in summer and contract in the low-temperature conditions of winter. The vehicle exterior is made up of multiple parts that expand and contract with changes in temperature, sometimes affecting the alignment of parts. The low-/high-temperature visual marketability test chamber is mainly used to evaluate the effects of temperature changes on plastic parts.

The test chamber is a temperature-controlled chamber big enough to fit a vehicle inside. Once a vehicle is placed inside, solar radiation is recreated using infrared lamps. To recreate solar radiation with a high degree of accuracy, light from the lamps is directed at the vehicle at an appropriate angle. Take plastic parts at the front of the vehicle, for example. Once the parts are heated to the core, the time having been taken to subject them to heat from solar radiation, seams and alignments between the steel hood and plastic parts are measured, and seams and alignments between different plastic parts are measured. Because plastic parts characteristically contract as the temperature falls, the chamber is cooled to a low temperature and, once the parts are sufficiently cooled, the same measurements as for high temperatures are carried out.

Because the strength of plastic parts diminishes as they expand due to heat, they are at risk of sagging. They might even become warped in a wave-like pattern. There is also the possibility of parts getting in the way of each other in between the seams, leading to peeling away of coatings or scratching. At low temperature, plastic parts contract, increasing the gap between them. Changes to seams and alignments due to deformation of parts as a result of temperature changes diminish marketability. Checking that this will not happen is the purpose of low- and high-temperature visual marketability testing. Personnel use a scale to carefully measure the displacement of seams and alignments caused by temperature changes, particularly in areas where the displacement would have a significant impact on marketability. Honda has its own original numerical standards for determining the adequacy of functionality and marketability, but visual checks by personnel are always undertaken as sometimes the human eye notices that something is not right even when the standards are met.

Allowances for expansion and contraction of parts are made from the start, drawing from past experience. Given that where and how parts should be affixed are incorporated into the design, the results of simulations are essentially confirmed in the field. This double-checking provides extra assurance of marketability.

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Corrosion Test Facilities (Salt Water and Mud Trough / Salt Water Shower / Vehicle corrosion Chamber)

Corrosion leads to a deterioration of marketability and degradation of metal caused by corrosion can lead to deterioration of driving safety functions. By recreating the burdens placed on vehicles associated with the day-to-day lifestyles of customers, such as rain, sunlight, and driving on roads sprayed with deicing agent, Honda seeks to enhance its knowledge about corrosion mechanisms and to observe the condition of the exterior and components related to driving functions in vehicles under development. Besides confirming that driving safety functions for driving, turning, and stopping will not be affected, Honda checks that marketability will not be diminished.

Corrosion testing facilities at the Tochigi Proving Ground consist of a salt water and mud trough (with a fresh water wash-off lane), a salt water shower, and a vehicle corrosion chamber. The three facilities are used in turn to carry out accelerated degradation tests. Conditions in each of a variety of regions where salt damage is severe are recreated and the effects on vehicles are intensified for a short turnaround in receiving the results.

Through repeated driving through the salt water and mud trough and the salt water shower, vehicles are subjected to environmental inputs they will receive in the market. They then undergo intensified corrosion inside the corrosion chamber. This process is then repeated. The salt water and mud trough is a pool of water mixed with salt (sodium chloride) and mud. This recreates a road that has been sprayed with deicing agent, of which a main ingredient is sodium chloride. The vehicle drives through this at a predetermined speed. Corrosion develops as steel reacts to the small amounts of oxygen in the water. Sodium chloride attaches to steel and absorbs water. As the surface of steel is covered in water for a longer time, the speed of corrosion increases.

After repeated driving through the salt water and mud trough, the vehicle is driven through a wash-off lane filled with clean fresh water. Although the purpose of the salt water and mud trough is to have salt-containing mud stick to the underside of the vehicle, the amount that adheres is too much. Mud is washed off to a certain degree to leave the right amount.

The purpose of the salt water shower is to have salt adhere to the vehicle body. As well as showering the vehicle with salt water rain, salt water is made to infiltrate the engine compartment.

After repeated driving through the salt water and mud trough and salt water shower, the vehicle is placed in the vehicle corrosion chamber. Conditions in the chamber are regulated to achieve hot and dry conditions, or humid conditions. Creating a corrosion-conducing environment enables short lead times for vehicle development. Air simulating the wind of motion is directed at the vehicle from the front to simulate real-world driving.

The test cycle is repeated a set number of times, after which visual checks of marketability and functionality are carried out. Driving safety functions are also evaluated. Here Honda makes use of original evaluation indicators developed in part through field studies.
Besides checking for corrosion itself, initial signs of corrosion and the condition of coatings are also checked. And rather than make judgements based solely on data obtained through sensors, visual checks by personnel are always carried out.

Once all test cycles are completed, the vehicle is taken apart. The enclosed body frame is severed to check the condition of the internal section. Such thorough tests and evaluations allow Honda to build up know-how, including insight into the parts of the vehicle that are prone to corrosion accumulation.

In all tests, engineers from related departments are on hand to undertake visual checks. They implement Honda’s Three Reality Principle—going to where the activity is to observe the actual products and the actual situation before making judgments. This leads to improvements in technology for ensuring that marketability and driving safety functions remain for the life of a vehicle.

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