"真空加浓器" can be translated into English as "vacuum enricher" or "vacuum thickening device" (though "vacuum enricher" is more commonly used in automotive contexts).
In the context of automotive carburetors (化油器 in Chinese), where vacuum-operated enrichment mechanisms are often found to provide additional fuel under certain conditions (like heavy acceleration or cold starts), "vacuum enricher" is the standard and widely recognized term.
So, if you're referring to the component in a carburetor that enriches the fuel mixture under vacuum conditions, "vacuum enricher" is the appropriate translation.