Mazda Technical Review
Online ISSN : 2186-3490
Print ISSN : 0288-0601
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Foreword
Special Edition for Mazda CX-30
  • Naohito Saga, Masahiro Yamada, Shusuke Kobiki, Ryosuke Morishige, Hiro ...
    2020 Volume 37 Pages 3-6
    Published: 2020
    Released: December 23, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    Under the human centric design approach, CX-30 is introduced as a completely new product which thoroughly realizes the value of the convenience as a compact crossover. The interior realizes the all passengers can spend a long drive comfortably while relaxing. The luggage space realizes the capacity and the usability which can respond to the various scene and needs without a stress. Technologies were interwoven with the latest knowledge such as driving position and Human-machine interface (HMI) and the evolved driving circumstance. CX-30 made politely to the detail and was crowded in order to support a wide lifestyle above up to now as well as feel this car and create a radiant life.

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  • Ryo Yanagisawa
    2020 Volume 37 Pages 7-11
    Published: 2020
    Released: December 23, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    Mazda CX-30, which is an entirely new entrant in the compact crossover SUV category, is the second model in Mazda's new-generation product lineup to feature the further-matured Kodo – Soul of Motion design concept, a concept rooted in traditional Japanese aesthetics. Inspired by the 'aesthetics of subtraction', an approach that lets beauty emerge by reducing elements rather than adding new ones, CX-30 has achieved styling with a finely-honed, powerful sense of dynamism.

    CX-30's styling has raised the car design to a higher level to satisfy two contradictory demands: the enhanced utility to win over a broad range of customers and the 'world's most beautiful crossover SUV' as a work of art. Based on the 'Sleek & Bold' design concept, its proportions combine the toughness of an SUV with a supple, flowing beauty that transcends the category.

    Design of CX-30's cabin is based on Mazda's 'Jinba-Ittai', human-centered design philosophy and traditional Japanese architecture with its use of Ma or empty space. The basic layout revolves around two areas with contrasting characteristics: a snug and condensed cockpit area for the driver, and a clean, airy open space around the front passenger. In addition to a genuinely refined, top-quality interior space achieved by great attention paid to every detail for improved fit and finish, four interior color schemes are offered to bring joy to customers and suit their different lifestyles.

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  • Ryotaro Nishida, Jiro Kato, Tomoaki Fujiyama, Takafumi Nishio, Hiroki ...
    2020 Volume 37 Pages 12-18
    Published: 2020
    Released: December 23, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    Mazda announced its long-term vision for technology development "Sustainable Zoom-Zoom 2030" and launched a new initiative in helping solve a variety of issues facing the earth, society and people through driving pleasure. Skyactiv-G 2.5T has been installed on relatively large vehicle models, such as the CX-9, the CX-8, the CX-5 and the Mazda6, to provide customers with driving pleasure, and has earned a good reputation for its high torque and acceleration response performance. This engine is now going to be installed on C-segment cars such as the CX-30 and the Mazda3 for North American market to offer customers responsive and torqueful driving. A water-cooled intercooler is used at maximum efficiency, and the engine has been significantly reduced in size. This paper introduces technologies employed for the new generation C-segment gasoline turbocharged Skyactiv-G 2.5T, which offers driving pleasure to many customers.

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  • Akihiro Nakata, Yosuke Morikawa, Satoshi Okamoto
    2020 Volume 37 Pages 19-26
    Published: 2020
    Released: December 23, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    Reducing the aerodynamic drag is essential for cutting CO2 emissions. However, the aerodynamic drag depends on the geometry of the vehicle, so both the aerodynamic performance and the design are necessary for the product development. We studied the Computational Fluid Dynamics (CFD) technique and aerodynamic drag reduction technology, focusing on the tire with rotation. First, we studied CFD validity of the flow around the tire with rotation, focusing on the tire shape and wheel rotation method. Secondly, we studied factors causing energy loss of flow by using the CFD, and achieved 3% Cd value reduction from the technology of previous generation. And, we adopted these new technologies on the aerodynamic development of CX-30. As a result, the vehicle achieved top level aerodynamic drag among the same class vehicles and realized the design concept.

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  • Yuji Kashimura, Takashi Oikawa, Tadashi Yoshimura, Hidetaka Goto, Atsu ...
    2020 Volume 37 Pages 27-32
    Published: 2020
    Released: December 23, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    CX-30 and Mazda3 were developed based on a common architecture as new generation vehicles. In the development for better ride comfort and vehicle dynamics, we set a target with aim to achieve a driver's stable head motion and "Jinba-ittai" performance based on the human-centered development philosophy. This target was achieved by newly-developed vehicle structural technology called Skyactiv-Vehicle Architecture. Following Mazda3, which was developed as a leading model equipped with this new technology, CX-30 was also developed with the adoption of the technology to realize the same characteristics in ride comfort and vehicle dynamics as those of Mazda3. We defined part of newly-developed technology that sustained Mazda3 characteristics as "fixed factor" technology, and rest of the technology that was changed from Mazda3 characteristics as "variable factor" technology. With a combination of these "fixed factor" and "variable factor" technology, we finally developed CX-30 in which a driver can feel same characteristics in ride comfort and vehicle dynamics as in Mazda3.

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  • Katsutoshi Shimada, Daisuke Umetsu, Yasumasa Imamura, Seiji Hidaka
    2020 Volume 37 Pages 33-38
    Published: 2020
    Released: December 23, 2020
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    Based on a long term vision, "Sustainable "Zoom-Zoom" 2030", Mazda aims to solve a variety of issues facing the "earth" "society" and "people" through "driving pleasure". Mazda AWD system has been developed by further pursuing "Jinba-ittai" to bring out human potential and boost the excitement of mind and body while aiming for ideal handling and real-world fuel economy performance.

    This article introduces "New generation i-ACTIV AWD" for CX-30 supported by significantly improved hardware and control system while sustaining the characteristics of the original "i-ACTIV AWD" mounted from 2012 CX-5.

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Technical Reports
  • Seiji Tanabe, Mikihiro Miyamoto, Noboru Yamagami, Akifumi Yamahiro, Se ...
    2020 Volume 37 Pages 39-44
    Published: 2020
    Released: December 23, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    For the vehicle reliability evaluation, Mazda has two test methods. The first one is the rig test using vehicle body or chassis part. The second one is the driving test using the actual vehicle. Both tests take important roles to evaluate vehicle durability and reliability.

    The driving test has been conducted by test-drivers who drive the test vehicle by day and night shifts, and there are some problems to be solved, which include prevention of judgement errors by the driver, improvement of labor environment, and shortening of evaluation period. We developed a rough-road durability test method using the autonomous driving device which can be the effective solution for these problems and verified it. This paper shows some application cases and the future prospects of the autonomous driving device.

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  • Yukifusa Hattori, Satoshi Harada, Seisuke Mitsunaga, Hiroaki Morita, H ...
    2020 Volume 37 Pages 45-49
    Published: 2020
    Released: December 23, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    Aims of Mazda's NVH performance development to enhance the value by realizing "quietness of good quality". That does not only reduce the sound pressure of the road noise from the road surface, and engine sound to make it easy to listen to conversation and music in the car, but also to be able to recognize a surrounding from those sounds to change while driving. In addition to "quietness realized from new Mazda3 of good quality",the sound paid its attention to being information to decide the next action for a person and thought that I brought it close to a state to be able to handle a car in a beck and call more by utilizing engine sound at the time of acceleration, the slowdown. We defined information, the timing to tell by a sound and built the engine sound that reflected these elements. When this engine sound could control unevenness of the vehicle speed, I hypothesized and proved it by the evaluation with the vehicle which implemented a simulator. We was able to fix the new design that I contributed to for handling a car on will as value of the sound.

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  • Tomohiro Izumiyama, Norihiro Nishida, Ryusuke Asahi, Hiroki Yamagata, ...
    2020 Volume 37 Pages 50-56
    Published: 2020
    Released: December 23, 2020
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    In order to reduce fatalities or serious injuries in traffic accidents, retaining a safer seated posture and proper occupant restraint is important, and the lack of them tend to cause serious abdominal injuries. The individual differences of the seated posture affects the occupant restraint by a seatbelt. This study aims to construct and commercialize technologies required for abdominal injury prevention based on the individual differences of the skeletal alignment in a seated posture and occupants' kinematics in a collision which was analyzed using human body models (HBMs). According to the analysis of individually different skeletal alignments in a seated posture, the seated postures are classified into two types: S-shape and kyphosis. For pelvis, the individual differences of ASIS shapes and the distances between ASIS and pubic symphysis were analyzed and incorporated into the HBMs to study occupants' kinematics. The analysis results of the kinematics indicated that the controlling the pelvic angle is essential to prevent the abdominal injuries.

    Based on the results, three new technologies were applied to Mazda3: a new seat design to achieve the S-shaped posture, a seat-integrated lap belt anchor to reduce pelvic rotation, and the knee airbag to sustain the occupant in position while limiting the force into the abdomen. The safer seated posture structure together with the newly designed restraint systems further improve the occupant protection performance, bringing Mazda's "human-centered design" philosophy into shape.

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  • Yoshitomo Umehara, Hideki Yonezawa, Koji Maruo, Keita Suenaga
    2020 Volume 37 Pages 57-62
    Published: 2020
    Released: December 23, 2020
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    For the realization of "Celebrate Driving", Mazda's brand essence, it is extremely important to perform high-precision molding of the complicated product shape which contributes to engine performance. Molding the product shape precisely, however, is not easy because a thin sand mold which is used for casting the cylinder head material is easily deformed by heat. To improve dimensional accuracy of the material, we need to suppress deformation and prepare a modified die with the expected dimension including minimum deformation. To achieve that, a technique to measure deformation precisely is required. Then we revealed an outbreak mechanism of heat deformation in the sand mold, improved the deformed model based on measured values and established a high-precision deformation prediction technology.

    We established a mold structure to suppress deformation by the heat and a model base development process which designs dimension correction in the initial stage of product development by using this technology. We achieved both functionality and productivity by adopting them to production preparation of Skyactiv-X cylinder head. This paper reports our activities.

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  • Yuichi Ariizumi, Shinjiro Koike, Seiya Kurahashi
    2020 Volume 37 Pages 63-68
    Published: 2020
    Released: December 23, 2020
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    Body Production Engineering Dept. has been tackling to establish the global production/supply system. This can realize both "Embodying the product value" that Mazda is pursuing and "High efficient and flexible production system" that can respond the change of market quickly.

    In 2019, the first Next-generation production line called "FML" (Flexible Module Line) was launched at the vacant lot of Ujina Body shop B2 line. This article introduces the concept, function, results, and challenges of this new line.

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  • Takahiro Kageyama, Shogo Sakomoto, Yuhki Kubo, Hideyuki Egusa, Toru Ka ...
    2020 Volume 37 Pages 69-74
    Published: 2020
    Released: December 23, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    Mazda aims to be a brand with a special bond with its customers. In order to provide cars that exceed the expectations of our customers, we, at the mold production department, believe that it is our mission to embody the "KODO - Soul of Motion" design theme, which represents the designers' aspiration, in the form of mass production cars. This article introduces the process innovation aimed at high-precision, high-efficiency production of molds to enhance the value offered to customers.

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  • Keisuke Yamakawa, Daiji Katsura, Takashi Yamamoto
    2020 Volume 37 Pages 75-80
    Published: 2020
    Released: December 23, 2020
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    Aiming to improve the value of cars, Mazda has been developing technologies with the concept of Material Model-Based Research (MBR) for the efficient development of innovative materials. In this study, aiming to achieve desired acoustic characteristics with a limited mass and volume of a porous sound-absorbing material that improves quietness in a car, we have developed technology that efficiently designs the microstructure of the material. This technology is a combination of the homogenization method that derives an average macro-structural property from the micro-structural property of the material and Biot model which is relatively simple prediction model for sound absorption/insulation performance. This technology enables highly accurate and efficient parametric calculations for microstructure's shape and size. Here we introduce the outline of this technology and the application of the technology to engine encapsulation.

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  • Kojiro Tanaka, Yuki Ogawa
    2020 Volume 37 Pages 81-85
    Published: 2020
    Released: December 23, 2020
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    In order to realize multi-material body, we are conducting researches on joining of aluminum and carbon fiber reinforced thermoplastic resin by using friction stir spot welding. In this report, the effects of aluminum surface treatment on strength properties were investigated by conducting shear tensile strength tests, fatigue tests, constant temperature and humidity tests, and thermal shock tests. As a result of comparative evaluation of two types of aluminum surface treatment for the purpose of improving chemical bond strength and giving anchor effect, both types showed a tendency to improve strength properties and reliability, and reduce variation, compared to the non-treatment material. Although the adhesiveness derived from the resin matrix components varies depending on the material, it is possible to improve robustness by using it in combination with aluminum surface treatment when using this joining process.

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  • Kohta Suzuno, Tohru Hokazono, Kazuaki Narahara, Masaharu Marumoto, Kot ...
    2020 Volume 37 Pages 86-91
    Published: 2020
    Released: December 23, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    This paper presents the development of intake air cooling with model-based development. Since the temperature of the intake air affects the efficiency of internal combustion engine, the technology of intake air cooling could be a key factor for the realization of fuel-efficient cars and the greenhouse gas reduction. In this study, we develop novel technologies to lower the temperature of the intake air based on numerical simulations and the sensitivity analysis via the adjoint method. The effectiveness of these methods is validated through the measurement of the temperature of the intake air system in a test vehicle.

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  • Kentaro Kawaguchi, Yuma Miyauchi
    2020 Volume 37 Pages 92-97
    Published: 2020
    Released: December 23, 2020
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    Boundary lubrication occurs at the start/stop of an engine and on the top/bottom dead centers of a piston. With the boundary lubrication, solid-solid contacts partially occur, which cause high friction resistance and wear. As a countermeasure, diamond-like-carbon (DLC) is an effective coating material with low friction and high wear resistance. For the Elasto-hydrodynamic lubrication calculations, Greenwood-Tripp (G-T) has been used as the model of the boundary lubrication phenomena, but the G-T model is not sufficient to reproduce the effect of coating materials and the microstructures of the contact interfaces. Therefore, the molecular dynamics method was used for modeling the effect of a molecular structure on the frictional properties in the boundary lubrication condition. The effect of the DLC molecular structure on the friction properties was clarified using a simulation model. To verify the friction mechanism, ring-on-disc friction tests and Raman spectroscopy analysis were performed.

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  • Ryohei Ono, Shun Osawa, Sekiyou Katsu, Keisuke Okihama, Yuji Harada, H ...
    2020 Volume 37 Pages 98-103
    Published: 2020
    Released: December 23, 2020
    RESEARCH REPORT / TECHNICAL REPORT FREE ACCESS

    While compression auto-ignition enabling lean burn combustion is effective for improving the efficiency of the internal combustion engine, controlling ignition timing and combustion duration are major challenges. In this study, we considered enhancing the combustion control by using an electric discharge which forms a flame kernel. When an electric discharge occurred in lean air-fuel mixture under a low pressure condition, we observed a flame kernel formed, unburned gas near the kernel heated, and then the flame going out. And when an electric discharge occurred during an intake stroke in a single-cylinder engine, we observed the auto-ignition timing advanced despite a longer time passes from electric discharge to compression auto-ignition. Then we performed a detailed chemical reaction analysis simulating an experiment to analyze the factors of this phenomenon. The result of analysis suggested that part of the fuel in unburned gas, which had been heated up by the kernel, was cleaved and generated chemical species, which survived until the latter half of engine cycle and induced compression auto-ignition. It also indicated that among the chemical species generated by the cleavage, HO2, in particular, greatly affected the effect of advancing of ignition timing.

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