Explosion-proof electrical generator system

Claim 1

An electrical generator comprising: (a) generally toroidal casing means with an open end, said casing means including: (i) radially outer side wall means, (ii) radially inner side wall means, (iii) annular outer end wall means extending between one end of said outer and inner side wall means, and (iv) inner end wall means extending across the toroidal casing and joining the other end of said inner side wall means, the casing means defining an outer annular recess bounded generally by said outer and inner side wall means and said annular outer end wall means, the annular outer recess generally surrounding a central recess bounded by said inner side wall means and said inner end wall means; (b) a stator assembly mounted on said inner side wall means in said outer annular recess; (c) circular cover means closing said open end of said casing means and extending across but axially spaced from said inner end wall means; (d) rotor means rotatable in said casing means and supported therein by a rotary shaft extending axially into the casing means, said rotor means including: (i) permanent magnet means; and (ii) outer cup means carrying said magnet means, said outer cup means including plate means oriented generally radially in the space between said circular cover means and said inner end wall means and extending outwardly to substantially axially overlie said outer annular recess, and side wall means extending from said plate means into said outer annular recess between said stator assembly and the outer side wall means of the casing means, the clearances and spacings between elements being such as to define a restricted flame path in the generator such that the temperature of any flame in the generator will drop sufficiently to prevent the ignition of the atmosphere in the immediate vicinity of the generator.