In hot climate regions, there is demand for improved thermal comfort for rear occupants in vehicles not equipped with a rear air conditioner. One solution to this challenge is a circulator mounted on the ceiling. The circulator is a product designed to enhance thermal comfort for occupants by circulating the air in the cabin. The conventional circulator design, which employs a cross flow fan with a large cross section, juts into the cabin space, because it is difficult to package. Consequently, the challenge for the circulator is to provide thermal comfort for rear occupants while taking up the minimum cabin space under the ceiling.
To solve this challenge, that is, to enable a substantially thinner structure, while retaining the same level of air flow delivered as before for the same thermal comfort as the conventional circulator, we divided the structure into an air outlet and an air blower. For the air outlet, it is technically necessary to improve the air flow volume gain factor (= volume of air delivered/volume of air blown out) acting in inducing the air around the outlet. For this reason, we devised a slit-shaped outlet that produces a high-air velocity jet and a guiding surface designed to maintain the high air velocity making use of the Coanda effect. The technical challenge associated with the air blower is to improve fan and motor efficiency in order to ensure a similar level of power consumption to the conventional circulator while achieving a higher pressure from a thinner structure. To meet this challenge, we developed a radial centrifugal air blower integrating a small motor into the fan. The results were that the heights of the air outlet and the air blower were reduced by 50% and 30%, respectively, as compared with the conventional model.