The latest technology of washer-dryers (Part 2): solving power saving, quietness and many other issues

    Today's washer-dryers need to meet many user requirements, including quietness, sterilization, space saving, drying and final washing effect, etc. Especially after the Great East Japan Earthquake, the demand for saving water and electricity has increased, so the "tilted drum washer-dryer" that uses an energy-saving heat pump to dry clothes is very popular.

    Since the late 1990s, there has been a demand for washing machines to be "environmentally friendly."

    In line with this trend, the "drum washer-dryer" was launched on the market in the early 2000s. This type of washing machine consumes much less water than the previous vertical washing machines, and gradually opened up the market with its excellent water-saving performance.

    However, the environmental friendliness of a drum washer-dryer is not just reflected in “water saving”.

    Compared with the next year's model (NA-VR1000), the tilt-drum washer-dryer (NA-V81) launched by Panasonic in 2004 reduced its rated power consumption for washing and drying from 4000Wh to 1840Wh, more than halved.

    Energy saving has been greatly improved because the 2005 model has replaced the 2004 model's heater for drying with a heat pump. The heat pump absorbs heat from the air outside the cylinder and releases it into the cylinder, which is significantly more energy efficient than a heater that uses electric heat to heat the air.

Heat pump is just as its name implies. It is a "pump" for "heat". The energy is not generated by electric heaters, but is used to absorb the heat from the outside and release it to the inside. With this principle, the heat energy transferred to the air in the drum (dryer) by the heat pump can reach several times the energy consumption.

    These are not the only advantages of heat pumps over heaters.

    "If we compare it to the heating method of an air conditioner, the heat exchanger that draws in air from the drum is equivalent to the outdoor unit of the air conditioner, and the heat exchanger that releases the air heated by the heat pump is equivalent to the indoor unit of the air conditioner," said Kenhiro Nakanishi, head of the second drum washing design group of the drum washing technology business group of the laundry cleaning division of Panasonic.

    According to the principle of heat pump, the "low temperature, high moisture content air" from the drum is first cooled by the heat exchanger on the cooling side (the side that absorbs heat from the air). At this time, the moisture in the air will condense on the blades of the heat exchanger.

    "The water that condenses on the leaves drains directly downward" (Nakanishi).

    This is like the "drying function" of an air conditioner, and it also "dehumidifies" the clothes. This reduces the amount of heat needed to dry the clothes, so the energy consumption is less than using a heater to dry the clothes.

    As mentioned above, heat pumps already have excellent energy-saving performance, and by improving heat pumps, efficiency has been further improved.

    As in washing, sensor technology also plays a role in energy saving in drying.

    If there are many fabrics that are easy to dry, not only rinsing but also drying will control energy consumption from the beginning. After drying starts, the washer-dryer will automatically determine the type of clothes to be dried through sensors. If the proportion of chemical fibers that are easy to dry is high, the number of revolutions of the compressor will be reduced to reduce power consumption.

    With the help of these technologies, the rated washing and drying power consumption of tilt-drum washer-dryers was reduced by approximately 18% in the six years from 2005 when heat pumps were first adopted to 2011.

When drying, two temperature sensors measure the temperature of the hot air entering and leaving the drum. Based on the temperature change, the type of clothing is determined. For easy-to-dry clothing, the drying time is reduced, saving time and electricity.

Power consumption change table

    The reason why drum washer-dryers are so popular is not just because they are environmentally friendly (caring for the earth). "Caring for clothes" is also one of the key points. Matsudahara, a consultant of the drum washing group of the product planning group of the laundry and cleaning division of Panasonic Electric, said: "If you simply use a heater with 100°C warm air for drying, the contact with high-temperature hot air may damage the clothes. The heat pump uses 65°C warm air for drying while dehumidifying, which is a low-temperature dehumidification and drying method, so it is more caring for clothes and has a better drying effect."

    Compared with vertical washer-dryers, drum washer-dryers' method of "stirring and drying clothes from top to bottom" is less likely to cause wrinkles.

    The hot dry air from the back of the drum is used to reduce uneven drying of clothes and dry them efficiently. When the "jet drying" button is pressed, the front of the drum will release jet air, which will make the clothes fly left and right while drying.

    "For clothes that wrinkle easily, limiting the drying weight to 3kg can reduce the degree of wrinkling" (Matsuhara).

Panasonic's tilting drum washer-dryer can reduce wrinkles by combining wide-area air blowing from the rear with jet air blowing from the front, according to the user's preference. The "jet air" is powerfully ejected from these holes, causing the clothes to "tumble".

    In addition, Songyuan also stated that "considerateness" is also a keyword for the washer-dryer.

    "With many women now active in society, more and more people wash clothes late at night after work or early in the morning. Therefore, quietness is a very important factor" (Matsuhara). The "sound" here refers to the vibration that reaches the next door or neighbors. Especially when spinning at high speed, if the clothes in the drum are concentrated on one side, the washing machine will vibrate violently and make noise. In order to prevent such vibration, the entire unit including the drum is supported by a suspension with excellent buffering performance.

    Furthermore, sensor technology also contributes to improved quietness.

    "The 3D acceleration sensor controls the way the drum swings during washing. During dehydration, if the swing is small, the number of revolutions is increased. If the swing is large, it is determined that the clothes are gathered together, and reasonable operations such as separating the clothes are automatically added" (Zhongxi).

The two suspensions supporting the drum absorb sway and vibration, improving the quietness during dehydration

3D acceleration sensor. It detects the rotation of the drum at any time. When the clothes are gathered in one place and cannot rotate smoothly, it automatically separates the clothes and distributes them evenly in the drum.

    The roller itself also uses special technology.

    "Calcium chloride liquid that does not freeze in winter is added to the plastic ring on the edge of the drum. After the drum starts to rotate, the liquid will move to the position where the clothes are concentrated and the opposite position, acting as a balancer to maintain the stability of the drum rotation" (Songyuan).

    With the help of the above technologies, the swing of the drum during rotation is reduced, and good quietness is maintained throughout the entire process of washing, rinsing and drying.

    Recently, a new keyword has emerged - "sterilization". "This function can prevent the black mold that is easy to grow in the washing machine in summer. Sterilization is no longer an additional function of washing machines, but a necessary technology. Mothers with children at home and even ordinary customers are very concerned about this function" (Songyuan).

    One of the designs that helps sterilize is the position of the small holes arranged on the side of the drum. The inner wall of the cylinder outside the drum is prone to black mold. During each dehydration, the high-speed water jet from the small holes of the drum will play a role in cleaning the inner wall. However, if the small holes are arranged in an overlapping manner in the horizontal direction, the corresponding inner wall will not be flushed by the water flow due to the partial obstruction between the holes, and the cleaning is not thorough enough.

    Therefore, in order to clean the entire inner wall without omission, the positions of the small holes on the side of the drum have been adjusted to different positions.

During rinsing and dehydration, clean water washes the inner wall of the drum outside. In order to prevent the connection between holes from being missed, the holes are arranged in a staggered manner in the horizontal direction. By the way, the triangular wave design improves the effect of making clothes float.

    In addition, Songyuan has listed a new keyword recently: "indoor drying".

    "Young women living alone are particularly reluctant to hang clothes outdoors. Moreover, some clothes are easily damaged if dried completely in a dryer, and many users are concerned about the high electricity bills" (Matsuhara).

    However, if you hang clothes that have only been dehydrated indoors, they may sometimes develop a bad smell.

    To this end, the tilting drum washer-dryer has prepared drying modes such as "standard", "complete", "fast" and "timed", and the small drum is also equipped with "indoor drying".

    "The cause of the stink is bacteria. 'Indoor drying' is a weaker type of drying. It starts at night and dries thoroughly during the day within 5 to 6 hours before bacteria multiply. It not only protects clothes and prevents wrinkles, but also does not produce odor" (Zhongxi).

    Another key word, "dedicated to single-person apartment living," reflects the modern society where the proportion of single-person apartment living is increasing regardless of gender, age or status. Panasonic's "small drum" is a tilting drum washer-dryer that complies with this trend.

    The small body with a width and depth of about 60cm can also meet the user's requirement of "wanting the same floor space" when replacing a vertical washer-dryer.

    In order to achieve miniaturization, the small drum uses Panasonic's own technology. Compared with products for the whole family, the small drum can hold less clothes. However, the height is relatively low, and the drum swings and vibrates less when rotating than large machines. Therefore, the small drum does not use a balancer, but uses the counterweight on the top plate to maintain the overall balance and prevent the housing from swinging.

    In addition, components such as the heat pump are concentrated in the space below the drum, which lowers the center of gravity and improves overall stability.

    As mentioned above, the small drum adopts a design concept that is completely different from that of the large machine, realizing a small tilting drum washer-dryer suitable for "apartment living alone".

Apartment-type "small drum" "NA-VH300L". Washing 7kg, drying 3.5kg. Can replace "vertical washing machine"

The upper part of the small drum. The compact space is filled with mechanical parts. The black block in the center is the "balance weight"

The lower part of the small drum. The structure is compact and includes a heat pump. The configuration of many components is neat and tidy.

    Thanks to advances in washing, rinsing and drying technologies, as well as a wide range of sensor technologies, today’s tilt-drum washer-dryers achieve amazing savings in time, water and energy.

    Based on these technologies, are there any tips to make their use smarter?

    Matsubara smiled and replied, "Put in the specified amounts of detergent and softener." The answer was surprisingly simple.

    Nakanishi explained the reason. "Some users put in more detergent than the specified amount in order to remove stains. However, if the amount is exceeded, the bubble sensor may judge that there is 'excessive foaming' during detection, causing the washing machine to drain water during the washing process. This will in turn reduce the cleaning power."

Water level sensor and bubble sensor. Two sensors are used to detect the water level and bubble amount in the drum. When there are too many bubbles, drainage and other controls will be performed to prevent the amount of bubbles from increasing.

    At the end of the interview, the author asked the two about their future dreams.

    Zhongxi answered seriously, "Create time for customers. In addition to the functions of a washing machine, the washer-dryer should also take care of other housework to give customers free time. The other is maintenance-free. After all, cleaning takes time, and I hope to develop a washer-dryer that will liberate customers more and more."

    Matsubara said with a smile: "The keyword of the aging society in the future will be maintenance-free. Smart washing machines that can stay clean just by leaving them there will probably become increasingly important. In addition, we cannot just consider the needs of customers, but must also create products that break old common sense and have completely new concepts."