Seven new technologies for new energy vehicles

At the People and Vehicles Technology Exhibition 2014 (Yokohama International Convention and Exhibition Center, Pacific) held on May 21-23, 2014, the latest technologies developed to win in the fierce global competition gathered together and won the automotive industry technicians. Closely. At this exhibition, the seven fields of low fuel consumption, compactness, lightweighting, cost reduction, autopilot, new materials, new jointing technology, and new development tools have emerged as interesting technologies. This article will introduce these new technologies to you.

Low fuel consumption: Toyota's SiC power semiconductors, to increase fuel efficiency by 10%

At this exhibition, the most popular and most visited visitors are the silicon carbide (SiC) power semiconductors exhibited by Toyota. Power semiconductors are the core components of the power control unit (PCU). The role of the PCU is to control the current of a drive motor such as a hybrid vehicle (HEV). The use of SiC for power semiconductors can reduce power losses, greatly reducing the size of the PCU and significantly improving fuel efficiency. Toyota has produced two types of SiC power semiconductors: a transistor that controls the current switch and a diode that controls the current in one direction (rectifier).

The transistor is left and the diode is right. Manufactured on Toyota's own production line.

SiC power semiconductors were jointly developed by Toyota Motor, Denso and Toyota Central Research Institute. Toyota Motor has set up a SiC cleaning shop in the company. Except that the wafers were made from the outside, other basics were done by Toyota.

Using SiC power semiconductors can maintain the same performance, reducing the PCU's volume to about 1/5.

The goal of the development is to replace the current Si (silicon) power semiconductors, to increase the fuel efficiency by 10%, and to reduce the size of the PCU to one-fifth of its original size. It is expected that the PCU equipped with SiC semiconductors will be put into practical use around 2020. Regarding the issue of cost, Toyota's commentator said that although the cost of SiC power semiconductors is high, we are paying more attention to the advantage of reducing fuel consumption. Therefore, we adopt it and hope to reduce costs elsewhere.

Low fuel consumption: Mitsubishi Electric presents the industry's smallest EV drive system using SiC power semiconductors

Mitsubishi Electric has developed the EV Motor Drive System, a EV drive system that uses SiC power semiconductors to reduce its size. The power module of the inverter uses SiC power semiconductors. Compared to existing systems using Si power semiconductors, the volume is reduced by half.

In addition to reducing losses, SiC power semiconductors also contribute to the miniaturization of inverters because the use of SiC power semiconductors can reduce the size of capacitors and coils in circuits compared to Si power semiconductors. After the Si transistor is turned off, it cannot be powered off immediately and will continue to be energized for a period of time (tail current), but there is no tail current in the SiC transistor. Because there is no tail current, the SiC transistor can achieve about 10 times higher frequency drive (high speed switching) than Si. Realizing high-frequency driving can reduce the amount of power stored in the switch during one cycle, and it can also reduce the size of the capacitor.

The industry's smallest EV drive system.

The inverter is integrated inside the housing of the motor and integrated. This not only simplifies wiring and wiring, but also merges the coolers of the motor and the inverter, thereby simplifying the water-cooled piping.

Mitsubishi Electric aims to make this drive system practical in 2023. It is hoped that the mass production effect of the popularity of SiC power semiconductors, coupled with miniaturization and integration, will gradually reduce costs.

Small size and light weight: 40% lighter than glass, Toyota's automatic loom realizes the resinization of the roof

Resinization of the car roof as a whole. The Toyota Automatic Weaving Machine has exhibited a multi-functional resin roof that has evolved from a Toyota Prius polycarbonate (PC) two-color molded roof and integrates many devices such as a solar battery and a camera. The device integrated with the roof includes a camera (front view camera and rear view camera), an antenna (shark fin antenna), brake lights (high brake light), and solar cells. When embedded in solar cells, the weight of the new resin roof can be reduced by 40% compared to the use of glass covers. In addition, the degree of freedom of the shape of the resin is high, and it is easy to realize a shape in which the glass is difficult to make. Because there is no dividing line (joint surface of the component), the resin also has the advantage of good appearance quality.

Small size and lightweight: Use bamboo fiber to make back seat back panel, 10% lighter than wood board

Compared with wooden boards, backboards made of bamboo fiberboard have higher strength and lighter weight.

NHK Spring has developed bamboo fiberboard for automotive interior materials. Using Thai-made bamboo fiber, a back seatback was made. The weight can be reduced by 10% compared to the current product using wood panels.

The reason why bamboo is considered is because bamboo is a natural resource and grows faster than trees, and it is expected to achieve stable purchases. Trees take nearly 60 years from planting to harvesting, and bamboo only takes about 3 years. Moreover, the yield of bamboo-made materials is higher than that of marijuana. Hemp crickets only use epidermis, and bamboo can be used in addition to branches and leaves.

The manufacturing method uses papermaking, which is the same as manufacturing and paper. Bamboo was pulverized into a fiber having a width of 0.2 mm and a length of about 50 to 60 mm, and was dried at a temperature of 120°C for 2 hours to obtain a bamboo fiber material. The material is made into paper, that is, mixed with water and polypropylene (having a particle size of about 200 μm) as a binder, and poured onto a metal wire to form a sheet having a thickness of 5 to 10 mm. Then, the sheet is heated at a temperature of 130 to 160° C. for about 1 minute, and stamping is performed when the sheet is heated to become soft.

Small size and light weight: Dacheng PLAS showcases structural materials that can be floated on the water, using a three-layer composite structure

Aluminum, polypropylene (PP), and aluminum form a three-layer structure.

Dacheng PLAS manufactures the seat frame using MetalSand, an aluminum/polypropylene (PP)/aluminum sheet structure, and displays it in water. The frame floats on the water surface, which shows its light weight. In fact, the company exhibited this material in 2013, but this time it has a clear purpose. The company has introduced the related technology in more detail.

MetalSand encapsulates polypropylene with a thickness of 4.0 mm between two aluminum plates with a thickness of 0.25 mm. Polypropylene is foamed using the MuCell process that blows in supercritical nitrogen, and MuCell is a patented process of the Japan Steel Institute. MetalSand has a flexural strength equivalent to a 1.6 mm thick steel plate (SPCC), but the weight is reduced from 108 g to 31 g, a reduction of about 70%. This is due to the fact that the polypropylene layer keeps the two aluminum plates at a certain distance, and the stress applied to each aluminum plate translates into tensile, compressive axial forces without bending. In addition to the simple structural materials such as the seat frame and the floor, it can also be used as a structural material and a heat insulation material.

For Suzuki HUSTLER. The wall thickness is reduced to 1.5mm to reduce weight. Use PA66 with 34% glass fiber added.

Small size and light weight: Germany's MAHLE introduces a lightweight cylinder head cover for cars, reducing weight by reducing wall thickness to 1.5mm

The Mahle company (Mahle) exhibited a lightweight cylinder head cover for Suzuki light weight that reduced the wall thickness to 1.5mm. The cap is injection moulded and the resin used is 34% glass fibre in polyamide 66. Suzuki has adopted such a cover on the engine R06A of the light vehicle HUSTLER (listed in January 2014). In the past, the cylinder head cover had a wall thickness of 2 mm. By reducing the thickness, the weight was reduced by 20%. In order to avoid undershooting and insufficient strength, ribs are provided on the sides from the valve to the other side.

Compact and Lightweight: Toyota Textile Develops New Separator, Volume Shrinks to 1/4

The role of the separator is to remove the oil droplets when recovering the blow-by gas (unburned mixed gas that leaks out to the crankcase). Toyota's new method of inertial impact impacts the separator's volume to about 1/4 of the past. This method is to set nozzles and non-woven fabrics on the way of the flow path, so that the nozzle can accelerate the leakage of air leakage and non-woven fabrics. contact. The oil droplets drip down when they penetrate the non-woven fabric. In the past, the method used to remove the oil droplets was to pass the leak through a labyrinthine flow path and separate the oil droplets using their own weight.