Small electric motors for dental equipment or the like

Claim 1

In a small electric motor, of the type used for dental equipment and the like, a rotor and stator defining between themselves an axially extending annular gap having a front end and a rear end, a housing having an interior accommodating said rotor and stator, said housing having a front chamber communicating with the front end of said gap and a rear chamber communicating with the rear end of said gap, partition means carried by and extending across the interior of said housing for closing said rear chamber and for providing on the side of said partition means opposite from said rear chamber a housing space for communicating with a source of compressed air, said housing being formed at its exterior, which is directed away from its interior, with at least one inlet passage communicating with said housing space and leading therefrom toward and communicating with said front chamber, and said housing also being formed at its exterior with at least one outlet passage having a front end communicating only with said rear chamber of said housing and having a rear end communicating freely with the outer atmosphere, and a closure sleeve carried by and surrounding said housing and closing said passages, except for said rear end of said outlet passage which communicates freely with the outer atmosphere, whereby cooling air can enter through said housing space into said inlet passage to flow therealong into the front end of said chamber where the cooling air reverses its direction and flows rearwardly through said gap between said rotor and stator into said rear chamber and from the latter into said outlet passage to flow therethrough to the outer atmosphere.