# US 6,102,657 A · Self-draining centrifugal pump having an improved inlet > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,102,657 A - Document ID: US6102657A - Status: Granted - Kind: A - Application number: 09/188,456 - Filed: 1998-11-09 - Granted: 2000-08-15 - Earliest claimed: 1998-11-09 - Assignees: Hydrabaths, Inc. - Inventors: Philip E. Chalberg; Patrick B. Healy - Web page: https://patentgrep.com/patent/US6102657A ## CPC - F04D 29/4273: {suction eyes} - Y10S 415/915: Pump or portion thereof by casting or molding - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract A centrifugal pump for use in whirlpool bath systems has an offset inlet chamber configured to provide a smooth transition from inlet to impeller which is suitable for one-step injection molding using two opposed molding cores that may be removed from the inlet in opposite directions. The chamber has a double "D" profile with opposite flattened side surfaces. The cross-sectional area of the chamber decreases progressively between a larger offset inlet aperture and a smaller, centered entrance to the impeller. This configuration improves pumping efficiency while reducing noise. ## Claims ### Claim 1 An improved centrifugal pump for use in whirlpool bath systems, the pump having an axis and an electric motor with a shaft along the axis and the shaft turning an impeller in a volute, an offset inlet positioned below the axis for delivering water to the impeller and volute through an entrance along the axis and an outlet for transferring pressurized water to a whirlpool bath system; the improvement comprising: an inlet chamber configured between said offset inlet and said entrance, said chamber forming a smooth transition from inlet to impeller and having a shape permitting one-step injection molding using two opposed cores that are removed from the molded inlet chamber in opposite parallel directions. ### Claim 2 (depends on 1) The improvement recited in claim 1 wherein the area of a cross-section along said inlet chamber is progressively smaller from said inlet to a location substantially adjacent said entrance. ### Claim 3 (depends on 1) The improvement recited in claim 1 wherein said inlet has a larger diameter than said entrance. ### Claim 4 (depends on 1) The improvement recited in claim 1 further comprising a drain channel between said volute and said inlet, said drain channel being positioned at a lower portion of said volute for substantially complete drainage of said volute upon deactivation of said pump and drainage of said whirlpool bath system. ### Claim 5 An improved centrifugal pump for use in whirlpool bath systems, the pump having an axis and an electric motor with a shaft along the axis and the shaft turning an impeller in a volute, an offset inlet positioned below the axis for delivering water to the impeller and volute through an entrance along the axis and an outlet for transferring pressurized water to a whirlpool bath system; the improvement comprising: an inlet chamber configured between said offset inlet and said entrance, said chamber forming a smooth transition from inlet to impeller and having a shape permitting one-step injection molding using two opposed cores that are removed from the molded inlet chamber in opposite directions; wherein said chamber comprises an interior wall having upper and lower sections, the cross-sections of which are in the shape of circular segments and having side sections which are substantially flat. ### Claim 6 (depends on 5) The improvement recited in claim 5 wherein the distance between said substantially flat side sections is shorter than the intersection of said inlet and said entrance. ### Claim 7 An improved centrifugal pump for use in whirlpool bath systems, the pump having an axis and an electric motor with a shaft along the axis and the shaft turning an impeller in a volute, an offset inlet positioned below the axis for delivering water to the impeller and volute through an entrance along the axis and an outlet for transferring pressurized water to a whirlpool bath system; the improvement comprising: an inlet chamber configured between said offset inlet and said entrance, said chamber forming a smooth transition from inlet to impeller and having a shape permitting one-step injection molding using two opposed cores that are removed from the molded inlet chamber in opposite directions; wherein said inlet and said entrance each have substantially circular cross-sections of unequal diameters, and wherein said chamber has cross-sections along substantially its entire length which are non-circular. ### Claim 8 (depends on 7) The improvement recited in claim 7 wherein said chamber cross-sections are progressively smaller in area from said inlet to entrance. ### Claim 9 (depends on 7) The improvement recited in claim 7 wherein said chamber cross-sections each have at least one flat surface. ### Claim 10 (depends on 9) The improvement recited in claim 9 wherein said chamber cross-sections each have two parallel straight surfaces. ### Claim 11 An improved centrifugal pump for use in whirlpool bath systems, the pump having an axis and an electric motor with a shaft along the axis and the shaft turning an impeller in a volute, an offset inlet positioned below the axis for delivering water to the impeller and volute through an entrance along the axis and an outlet for transferring pressurized water to a whirlpool bath system; the improvement comprising: an inlet chamber configured between said offset inlet and said entrance, said chamber forming a smooth transition from inlet to impeller and having a shape permitting one-step injection molding using two opposed cores that are removed from the molded inlet chamber in opposite directions; further comprising an air induction tube connected to said chamber for effectively stopping pumping action without deactivating said motor.