| 摘要 |
<p>An injecting nozzle for injecting reactants into the mixing chamber of a foam machine mixing head wherein the needle which seals the nozzle opening also controls the communication between the feed conduit and the return conduit of the recycle system. The needle by means of an annular groove carried on its shaft or on the nozzle housing or by "means" of annular grooves on both allows the reactants to recycle through the return conduit when the nozzle opening is sealed but prevents such recirculation when the nozzle opening is open. Thus, the recycle path and the pouring path are identical or almost so and any dynamic disturbance upon changing of modes is eliminated.</p> |
