# US 2019/0316595 A1 · Centrifugal pump > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0316595 A1 - Document ID: US20190316595A1 - Status: Published application - Kind: A1 - Application number: 16/472,596 - Filed: 2017-12-22 - Published: 2019-10-17 - Earliest claimed: 2016-12-23 - Assignees: Grundfos Holding A/S - Applicants: Grundfos Holding A/S - Inventors: Helge GRANN; John Frigård NIELSEN; Erik Bundesen SVARRE; Per Frost VEDSTED - Web page: https://patentgrep.com/patent/US20190316595A1 ## CPC - F04D 1/00: Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps (adapted for pumping specific fluids F04D7/00; priming or boosting F04D9/00) - F04D 29/12: using sealing-rings - F04D 1/06: Multi-stage pumps (F04D1/02, F04D13/10 take precedence) - F04D 29/10: Shaft sealings - F04D 29/126: {especially adapted for liquid pumps} - F04D 29/128: {with special means for adducting cooling or sealing fluid} - F16J 15/3464: {Mounting of the seal} - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - F16J: PISTONS {(specially adapted for dampers F16F9/32)}; CYLINDERS; SEALINGS ## Abstract A cartridge seal is provided for sealing a shaft (4) with respect to a housing (2) and is intended to be a slide ring seal arrangement (12) for a centrifugal pump. The cartridge seal includes a shaft protection sleeve which is rotationally connected to the shaft (4) by a retaining ring, a support (24) for incorporating the cartridge seal into a housing opening of the pump housing (2), a slide ring which is rotationally connected to the shaft protection sleeve and a counter slide ring which is rotationally connected to the support (24), as well as an enclosed space (30) within the sealing arrangement. The space (30) is fluidically connected to a sealing gap formed between the slide ring and the counter slide ring, and is at least partially prefilled with liquid in order to prevent dry running when the pump is operated for the first time. ## Claims ### Claim 1 A method for manufacturing a shaft seal arrangement for sealing a shaft with respect to a surrounding casing, the method comprising the steps of: providing a seal arrangement comprising slide rings with a sealing gap between the slide rings; forming a cavity which within the seal arrangement which is in fluid-leading connection with the sealing gap between the slide rings; at least partially filling the cavity with a fluid during an assembly of the seal arrangement. ### Claim 2 A single-stage or multi-stage centrifugal pump comprising: a pump casing; a shaft which is rotatably arranged in the pump casing; at least one impeller arranged on the shaft, for the delivery of fluid; a shaft seal arrangement between the shaft and an opening of the casing, through which opening the shaft is led, with a closed-off cavity within the seal arrangement, the closed-off cavity is at least partly pre-filled with a fluid, wherein the fluid has been filled on assembly of the seal arrangement. ### Claim 3 (depends on 2) A single-stage or multi-stage centrifugal pump according to claim 2, wherein the shaft seal arrangement comprises two slide rings with axial sliding surfaces, of which one of the two slide rings is rotationally fixedly connected to the shaft, and the other, the stationary slide ring is rotationally fixedly connected to the pump casing, the cavity is arranged directly adjacent to the stationary slide ring, and at an opposite side which is away from the stationary sliding surface, and the closed-off cavity is fluid conveyingly connected to the sealing gap between the sliding surfaces. ### Claim 4 (depends on 3) A single-stage or multi-stage centrifugal pump according to claim 3, wherein the closed-off cavity is arranged above the stationary slide ring given designated operation of the pump. ### Claim 5 (depends on 3) A single-stage or multi-stage centrifugal pump according to claim 3, wherein the closed-off cavity is only partly filled with the fluid, preferably to a share of at least 10% to 50% of the volume of the cavity. ### Claim 6 (depends on 3) A single-stage or multi-stage centrifugal pump according to claim 3, wherein the closed-off cavity is sealed to to pump surroundings, by a cavity sealing ring, and the cavity sealing ring is configured as a lip sealing ring and/or labyrinth sealing ring. ### Claim 7 (depends on 6) A single-stage or multi-stage centrifugal pump according to claim 6, wherein the cavity sealing ring has a U-shaped or L-shaped ring cross section, wherein a limb of a U of the U-shape, which is on a shaft side, is configured longer than the other one, and the web of the U/L is arranged on a wall which delimits the cavity and which is distanced to the stationary slide ring. ### Claim 8 (depends on 6) A single-stage or multi-stage centrifugal pump according to claim 6, wherein the cavity sealing ring is fastened on a carrier which is materially connected to the cavity sealing ring, to which carrier the stationary slide ring is fastened at a casing side. ### Claim 9 (depends on 1) A single-stage or multi-stage centrifugal pump according to claim 1, wherein the shaft seal arrangement comprises two slide rings with axial sliding surfaces, of which one of the two slide rings is rotationally fixedly connected to the shaft and the other, the stationary slide ring is rotationally fixedly connected to the pump casing, and the cavity (30b, 30c) is arranged on the carrier (24b) or on the stationary slide ring (22c) and is fluid conveyingly connected to the sealing gap between the sliding surfaces. ### Claim 10 (depends on 6) A single-stage or multi-stage centrifugal pump according to claim 6, wherein the cavity sealing ring has an I-shaped, X-shaped or W-shaped ring cross section. ### Claim 11 (depends on 1) A single-stage or multi-stage centrifugal pump according to claim 1, wherein the seal arrangement is formed by a pre-filled cartridge seal. ### Claim 12 A cartridge seal for sealing a shaft with respect to a casing, as a shaft seal arrangement for a centrifugal pump the cartridge seal comprising: a shaft protection sleeve; fixing means for providing a rotationally fixed connection of the shaft protection sleeve to the shaft; a carrier for integrating the cartridge seal into a casing opening; a rotating slide ring rotationally fixedly connected to the shaft protection sleeve; a stationary slide ring rotationally fixedly connected to the carrier; and a closed cavity, wherein the closed-off cavity is fluid conveyingly connected to a sealing gap which is formed between the rotating slide ring and the stationary slide ring, and the closed-off cavity is at least partly pre-filled with a fluid. ### Claim 13 (depends on 12) A cartridge seal according to claim 12, wherein the closed cavity is arranged between the shaft protection sleeve, the carrier and the stationary slide ring, or on the carrier or on the stationary slide ring. ### Claim 14 (depends on 12) A cartridge seal according to claim 12, wherein the closed-off cavity is only partly filled with the fluid, to a occupy at least 10% to 50% of the cavity volume. ### Claim 15 (depends on 13) A cartridge seal according to claim 13, further comprising sealing means for sealing the carrier with respect to the shaft protection sleeve, the sealing means comprising a cavity sealing ring which is configured as a lip seal and/or labyrinth seal. ### Claim 16 (depends on 15) A cartridge seal according to claim 15, wherein the cavity sealing ring has a ring cross section which is I-shaped, L-shaped, U-shaped, X-shaped or W-shaped. ### Claim 17 (depends on 15) A cartridge seal according to claim 15, wherein that the cavity sealing ring has a U-shaped ring cross section, wherein a limb of the U-shape which is on a shaft side is configured longer than another limb of the U-shape, and a web of the U-shape is arranged on a wall which delimits the cavity and which is distanced to the stationary slide ring, wherein the cavity sealing ring is fixedly connected to the carrier. ### Claim 18 (depends on 12) A cartridge seal according to claim 12, wherein the rotating slide ring is axially moveably arranged on the shaft protection sleeve, the rotating slide ring is subjected to spring force in a direction of the stationary slide ring and a sealing means seals the rotating slide ring with respect to the shaft protection sleeve. ### Claim 19 (depends on 1) A cartridge seal according to claim 1, wherein the closed-off cavity is connected to the sealing gap between the sliding surfaces, via a radial gap between the stationary slide ring and the shaft protection sleeve. ### Claim 20 (depends on 1) A cartridge seal according to claim 1, wherein the shaft protection sleeve passes through the carrier and is connected to a fastening ring which is provided for the rotationally fixed connection of the shaft protection sleeve to the shaft, and the fastening ring forms a wall which is adjacent the cavity sealing ring.