Fluid delivery devices using a pair of meshed external gears, in
spite of no reciprocating component for fluid delivery enabling low
rotational vibration, the high
noise due to the
trapping phenomenon, and the teeth bouncing contact due to undesired large backlash heretofore afforded in the
gear manufacturing process,
restrict the employments in the industrial field requiring quiet environment such as
electric motor vehicles or room services.Accordingly, a
gear pump or motor or a gear refrigerating compressor comprising a shaft gear and a driven gear meshed rotatably within a gear chamber formed with a housing and opposite side walls, which delivers fluids from a inlet chamber to a outlet chamber; a backlash of the meshed gears having fluid-leak-tight clearance; a
closed chamber provided in a internal portion of at least a side wall; an opening provided on a side wall from which a communication passage extends to a
closed chamber; and at least a elastic disc
capsule contained in the
closed chamber, comprising a pair of concaved elastic disc plate abutted and sealed against each other with gas inside, of which occupying volume varies elastically subject to the
fluid pressure therein enabling to absorb or expel the squeezed fluid in the trapped interstice during the
trapping period of the interstice, whereby the fluid entrapped in the interstices isolated by the fluid-leak-tight backlash suppressing the
pressure transmission inwardly or outwardly, whereof volumetric variation during the
trapping period is compensated by the compression or expansion of the elastic disc
capsule, suppressing pressure pulse and
air bubble generation and eliminating the teeth bouncing contact, achieving a
low noise, low vibration and high efficiency
gear pump or motor or refrigerating compressor.