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Hitachi

Elevators, Escalators

Developer interview Developing the World’s Fastest Elevator
[Comfort]

Unprecedented Technology Takes Ride Quality
into the Highest Class

The elevators Hitachi delivered to Guangzhou CTF Financial Centre, a skyscraper complex in China, were certified by Guinness World Records as “the world’s fastest elevator”*. Running at a rated speed of 1,260 m/min, it takes them around 42 sec to climb 440 m from the first floor to the hotel lobby on the 95th floor. The essential elements in our achievement of the World’s Fastest Elevator were drive performance, safety, and comfort. Traveling at ultra-high speed introduces factors which had not previously been problematic, and which reduce comfort for users. Hitachi developed an array of new technologies to solve the problem.

* Certified by Guinness World Records on September 10, 2019, as holding the official record title of “The fastest lift (elevator).”

Diverse Problems Which Arise when Running at Ultra-high Speeds

In ordinary elevators, the problems affecting ride quality are vibration and noise. In this case, the height difference of 440 m introduced the new problem of air pressure change. Also, the speed of 1,260 m/min, different by an order of magnitude, exacerbates the problems of vibration, noise, and air pressure change many times over. Ryohei Kawabata of the Mechanical Device Development Group, which worked on structural design for the car frame, says “When speed gets up to 1,260 m/min, airflow and tiny bumps and curves in the guide rails have huge impacts on vibration and noise.”

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Active guide system

The vertical active guide system was developed as a technology to halve the vibration caused by bumps in the guide rail. In the active guide system, car vibration is detected by acceleration sensors, and spring force is controlled by actuators, to eliminate vibration. We had already introduced this technology on previous products, but in this case, we installed acceleration sensors in four locations, for up, down, left, and right, with an active guide system. Kawabata says “The faster the elevator goes, the more it is influenced by various disturbances. In addition to horizontal oscillation, the car can also rotate. To suppress yawing, pitching, and rolling, we installed active guide systems on the top of the car as well as the bottom. That configuration allowed us to address complex oscillations. But that increased the degrees of freedom, which made the work of adjustment that much harder.”

Ryohei Kawabata
Mechanical Device Development Group
Device Development Dept.
Development Div.
Development & Production Management Div.
Elevator & Escalator Div.
Ryohei Kawabata

Exerting Hitachi Group Synergies

Within elevator noise, mechanical noise is the main problem  at low speed, but wind noise increases with speed. So we introduced the capsule structure used in high-speed trains. Yasushi Ito, who worked on structural design with Kawabata, says “We reduced wind resistance by using a streamlined end like on high-speed trains, and we designed the car so that noise does not leak into the interior.” Hitachi leveraged its world-leading high-speed train expertise in the design. Ito says “To study the optimum form, we built and experimented on numerous mockups, and used fluid analysis software to validate their effects. In this case, we used software that had a proven record on high-speed trains, which enabled us to get quickly to analysis results close to those from real machines.”

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The problem of air pressure change in elevators comes from the feeling of ear pressure. That sensation is felt more strongly when the elevator goes down than when it goes up. Therefore, we restrict the speed of the elevator on the way down, and we developed a new system to mitigate the feeling of pressure by controlling interior air pressure, to modulate interior air pressure changes. Ito says “We soften the intensity of pressure change to relieve the feeling of ear blockage. Modulating air pressure makes users feel the sensation of ear pressure before it becomes uncomfortable, and produces a pattern of air pressure change that makes people actively release pressure in their ears. We then performed sensory assessment on the created patterns in an air pressure simulator. With the participation of multiple test subjects, the simulations assessed whether discomfort was mitigated in practice. Hitachi Group companies with relevant expertise were asked to help with the assessment methods. That was another way that Hitachi Group synergies came into play.

Yasushi Ito
Mechanical Device Development Group
Device Development Dept.
Development Div.
Development & Production Management Div.
Elevator & Escalator Div.
Yasushi Ito

Going Forward with the Confidence that Comes from Generating New Value

In fact, elevators open and close their doors frequently, and there are many sliding parts, so the structure is prone to air leakage. Enhanced car airtightness was a precondition for controlling air pressure modulation. In the initial design, however, we were unable to ensure airtightness, so we couldn’t raise air pressure as we wanted. Hiroyuki Tateyama, who worked on tasks such as assessing the strength of the car frame and airtightness of the car for the Elevator and Escalator Product Quality Assurance Dept., says “We used caulking material to raise airtightness around the car, but even so it was hard to raise air pressure, and running fans faster in the pressure control system just made more noise.”

The solution to the problem was proposed by Tomotaka Kariya of the Mechanical Device Development Group. Kariya says “I thought of a system which would use the airflow that is naturally generated by air pressure change to close the gaps, and the idea even got a patent. It involved the decision to change the structure with only a year to go before the shipment deadline, so it was tough to pitch the idea to the people involved.” Kariya’s idea made a big contribution to raising airtightness.

Hiroyuki Tateyama
Elevator and Escalator Products Quality Assurance Dept.
Quality Assurance Div.
Hiroyuki Tateyama

 

But just changing the design didn’ t mean that everything would go well. The hardest struggle was the final adjustment after the cars were assembled on site. To deliver the elevators, they had to get certified by an official Chinese authorization agency. That required braking experiments to bring the elevator from high speed to an emergency stop, which involved considerable mechanical shocks. It was possible that the comfort that we had worked so hard to build in might be lost. Tateyama says “Under intense pressure, we all worked together, including the on-site workers, to make adjustments in the spirit of making the elevators even better than they had been before the testing. It was really tough, but we were all delighted to have finished the elevators into a good product and delivered them to the customer.”

Young staff like Kawabata and Ito, who were assigned to the project in their first year in the company, took the lead in this project to develop the world’s fastest elevator. While respecting the cooperation of many seniors and experts, they applied their free imagination and passion to the development of unprecedented new technologies. Kariya says “In ordinary development, there are almost no opportunities to add in this many new technologies at once. Now I have the confidence that comes from making something new from an unknown starting point, so I want to put the experience I gained to work in future development.” The young staff who accumulated precious experience in this project will take the lead in building the future of Hitachi elevators.

Tomoki Kariya
Mechanical Device Development Group
Device Development Dept.
Development Div.
Development & Production Management Div.
Elevator & Escalator Div.
Tomoki Kariya
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