Patent ID: 8662872

Claim:
An oven ( 10 ) for the thermal conditioning of preforms made of a thermoplastic material which comprises at least one cooling circuit ( 16 ) using the circulation of a main flow of cooling air (A) which, from the upstream side to the downstream side, sequentially traverses inside the oven ( 10 ) at least: one cooling air intake area ( 16 a ), which comprises at least one air intake duct ( 18 ) through which the said main flow of cooling air (A) can flow, from the outside of the oven ( 10 ) to the inside of the oven ( 10 ), one heating area ( 16 b ) which is supplied with air by the intake duct ( 18 ) and which comprises means ( 22 ) for heating the preforms, and one air extraction area ( 16 c ) into which at least one air extraction duct ( 42 ) opens, the oven ( 10 ) comprises a confining housing ( 46 ) that extends from the air extraction duct ( 42 ) to at least the heating area ( 16 b ) and is capable of insulating at least the said heating area ( 16 b ) with respect to the outside of the oven ( 10 ) in order to prevent the pollution of the inside of the oven ( 10 ) by airborne polluting particles, characterized in that the confining housing ( 46 ) comprises at least one so-called secondary air inlet opening ( 54 ) which is arranged downstream of the heating area ( 16 b ) in such a way that a secondary flow of air (B) flows from outside the oven ( 10 ), directly through the said secondary air inlet opening ( 54 ), to the air extraction duct ( 42 ).