Patents by Inventor Vishnu M. Sishtla

Vishnu M. Sishtla has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20220011026
    Abstract: A vapor compression system and method for operating the vapor compression system are provided. The vapor compression system includes a first compressor, a second compressor, a condenser, and at least one check valve disposed between the first compressor and the condenser. The method provides for the transmitting of a shutdown command to at least one of the first compressor and the second compressor, at least one of the first compressor and the second compressor including a rotating shaft and a magnetic bearing, the magnetic bearing having an active mode and an inactive mode, the magnetic bearing levitating the rotating shaft in the active mode. The method further provides for the monitoring of at least one of a rotational speed of the rotating shaft and a differential pressure over the check valve for a preset time, wherein the magnetic bearing remains in the active mode at least during the preset time.
    Type: Application
    Filed: July 1, 2021
    Publication date: January 13, 2022
    Inventors: Vishnu M. Sishtla, Jun Cao, Kai Deng
  • Publication number: 20220010802
    Abstract: An example centrifugal compressor includes a housing that defines an inlet chamber and includes first and second openings that define a recirculation passage in fluid communication with the inlet chamber. An impeller is disposed within the housing and is rotatable about a longitudinal axis to draw fluid into the inlet chamber. The first and second openings are at different axial locations along the longitudinal axis. A plurality of inlet guide vanes are rotatable and situated in the inlet chamber. The centrifugal compressor includes a ring and a controller for moving the ring along the longitudinal axis between a first position and a second position when rotating the inlet guide vanes. The ring obstructs at least one of the first and second openings more in the second position than in the first position.
    Type: Application
    Filed: September 23, 2021
    Publication date: January 13, 2022
    Inventors: Vishnu M. Sishtla, William T. Cousins
  • Publication number: 20210404720
    Abstract: A compressor assembly, a vapor compression system incorporating the same, and a method for operating the vapor compression system are provided. The compressor assembly includes a motor for driving a rotating shaft, a foil bearing for supporting the rotating shaft, a compression mechanism for increasing the pressure of a working fluid, a supply line in fluid communication with the compression mechanism, and a heating apparatus for heating the working fluid. The supply line is configured for injecting the working fluid (e.g., from downstream of the compression mechanism) toward the foil bearing. The method provides for the monitoring of the temperature of the working fluid. When the temperature of the working fluid is less than 3° F. of superheat it is heated prior to being injected toward the foil bearing. The heating of the working fluid prevents, or at least mitigates, liquid from being transferred to the foil bearing.
    Type: Application
    Filed: June 11, 2021
    Publication date: December 30, 2021
    Inventors: Vishnu M. Sishtla, Yifan Qiu
  • Patent number: 11187249
    Abstract: The present invention provides a silencer, including: a silencer housing having an annular plate-like structure, with an annular mounting chamber formed therein; a silencing pad disposed in the mounting chamber; and a positioning portion disposed on the silencer housing and used for fastening the silencer housing. The silencer according to the embodiment of the present invention has an integrated structure, and can desirably avoid the problem of mounting unflatness in a separated structure. Moreover, the silencing pad therein is disposed to surround the entire silencer, which can provide a sound absorption and noise reduction effect more efficiently.
    Type: Grant
    Filed: January 23, 2017
    Date of Patent: November 30, 2021
    Assignee: CARRIER CORPORATION
    Inventors: Vishnu M. Sishtla, Kai Deng, Zhanbo Du
  • Publication number: 20210364209
    Abstract: A method of operating a heat exchanger system in which a compressor, which is drivable by a motor, is fluidly interposed between an evaporator and a condenser following receipt of a shutdown command is provided. The method includes positioning inlet guide vanes (IGVs) of the compressor in a first position in the event of at least one of a first precondition being in effect and the first and a second precondition both not being in effect. The method further includes positioning the IGVs in a second position in an event the first precondition is not in effect but the second precondition is in effect, ramping a speed of the compressor down until a third precondition takes effect, removing power from the motor and positioning the IGVs in the first position once power is removed from the motor.
    Type: Application
    Filed: April 8, 2019
    Publication date: November 25, 2021
    Inventors: Vishnu M. Sishtla, Scott A. Nieforth
  • Patent number: 11156226
    Abstract: An example centrifugal compressor includes a housing that defines an inlet chamber and includes first and second openings that define a recirculation passage in fluid communication with the inlet chamber. An impeller is disposed within the housing and is rotatable about a longitudinal axis to draw fluid into the inlet chamber. The first and second openings are at different axial locations along the longitudinal axis. A plurality of inlet guide vanes are rotatable and situated in the inlet chamber. The centrifugal compressor includes a ring and a controller for moving the ring along the longitudinal axis between a first position and a second position when rotating the inlet guide vanes. The ring obstructs at least one of the first and second openings more in the second position than in the first position.
    Type: Grant
    Filed: February 11, 2019
    Date of Patent: October 26, 2021
    Assignee: CARRIER CORPORATION
    Inventors: Vishnu M. Sishtla, William T. Cousins
  • Publication number: 20210317837
    Abstract: The invention relates to a centrifugal compressor and a method of operating the same. A centrifugal compressor of the invention includes an impeller, a diffuser and a variable diffusion system, wherein the diffuser is disposed downstream of the impeller and has a respective diffuser frame that defines at least a channel through which the fluid flows from the impeller; moreover, the variable diffusion system comprises a movable body that is able to move relative to the channel and an electromagnetic actuating device, and the electromagnetic actuating device controls the movable body to move relative to the channel in an electromagnetic driving manner. The variable diffusion system of the centrifugal compressor in the invention is simple in implementation structure, low in cost, easy to operate and good in stability and reliability.
    Type: Application
    Filed: December 15, 2020
    Publication date: October 14, 2021
    Inventors: Jun Cao, Vishnu M. Sishtla, Sheng Chen, Hao Zhao
  • Publication number: 20210293236
    Abstract: A screw compressor is provided and includes a housing (11), helical screws (21, 24) disposed within the housing (11) for rotation about respective rotational axes (RA1, RA2) in a mutually engaged relationship, at least one stator (30, 40) disposed within the housing (11) about a corresponding one of the helical screws (21, 24) and a conductive element (50, 60). The conductive element (50, 60) is wound about the at least one stator (30, 40) such that current applied to the conductive element (50, 60) generates a flux field by which the corresponding one of the helical screws (21, 24) is driven to rotate about the corresponding rotational axis (RA1, RA2).
    Type: Application
    Filed: September 13, 2017
    Publication date: September 23, 2021
    Inventors: Vishnu M. Sishtla, Jagadeesh Tangudu
  • Publication number: 20210285453
    Abstract: A compressor with a touchdown bearing and a supply line for injecting a working fluid toward the touchdown bearing, and a vapor compression system incorporating the same are provided. The supply line injects working fluid approximately continuously when the compressor is operational. The compressor includes a magnetic bearing for levitating the rotating shaft when the compressor is operational. The touchdown bearing is used to support the rotating shaft when the compressor is shutdown. The touchdown bearing may be disposed, at least partially, between a pair of races. The injecting of the working fluid may cause the touchdown bearing to rotate between the races. The injecting of the working fluid may help mitigate a buildup of a debris between the touchdown bearing and the races.
    Type: Application
    Filed: February 26, 2021
    Publication date: September 16, 2021
    Inventor: Vishnu M. Sishtla
  • Patent number: 11112148
    Abstract: A vapor compression system (20; 400; 420) comprises: a compressor (22) having a suction port (40) and a discharge port (42); a heat rejection heat exchanger (58) coupled to the discharge port to receive compressed refrigerant; a heat absorption heat exchanger (88); a first lubricant flowpath (120, 126) from the heat rejection heat exchanger to the compressor; a second lubricant flowpath (121, 126) from the heat absorption heat exchanger to the compressor; at least one lubricant pump (190); and a controller (900) configured to control lubricant flow along the first lubricant flowpath and the second lubricant flowpath based on a sensed fluctuation.
    Type: Grant
    Filed: August 10, 2017
    Date of Patent: September 7, 2021
    Assignee: Carrier Corporation
    Inventors: Scott A. Nieforth, Vishnu M. Sishtla
  • Publication number: 20210270279
    Abstract: An exemplary compressor system includes a compressor having a fluid inlet and a fluid outlet. An isolation valve connects the fluid outlet of the compressor to a condenser. A controller is communicatively coupled to the isolation valve and the compressor. The controller includes a memory storing instructions configured to cause the controller to detect one of a surge event and a surge event precursor and restrict an opening in the isolation valve in response.
    Type: Application
    Filed: May 11, 2020
    Publication date: September 2, 2021
    Inventors: Vishnu M. Sishtla, William T. Cousins
  • Publication number: 20210270289
    Abstract: A centrifugal compressor includes an impeller configured to drive fluid along a fluid flowpath via a plurality of discrete passages. Each of the discrete passages includes a discrete passage exit. A diffuser portion is disposed circumferentially about the impeller. The diffuser portion includes a plenum connected to each exit of the discrete passages via a plurality of diffuser inlets and an equalization plenum defined adjacent to the impeller. The equalization plenum is fluidly connected to each discrete passage exit via a corresponding slot.
    Type: Application
    Filed: July 10, 2020
    Publication date: September 2, 2021
    Inventors: Vishnu M. Sishtla, William T. Cousins
  • Publication number: 20210270275
    Abstract: An electric motor includes a stator and a rotator that is configured to rotate with respect to the stator. The stator has a length Ls and the rotor has a length Lr. The length Lr of the rotor is less than the length Ls of the stator such that the rotor does not overhang the stator. A compressor and a method of compressing a fluid are also disclosed.
    Type: Application
    Filed: May 11, 2020
    Publication date: September 2, 2021
    Inventor: Vishnu M. Sishtla
  • Patent number: 11105203
    Abstract: A balancing weight mountable within a balance hole of a rotary component includes a cylindrical body having a desired weight. An opening is formed in a portion of the body to define a hollow passageway and a mechanism couples the cylindrical body within an interior of the balance hole.
    Type: Grant
    Filed: December 11, 2018
    Date of Patent: August 31, 2021
    Assignee: CARRIER CORPORATION
    Inventors: Vishnu M. Sishtla, Jing Chen
  • Publication number: 20210262478
    Abstract: A bearing support (26) for a compressor (10) includes an annular body. The annular body includes a circle opening (28) that is configured to receive a bearing (21) and a shaft (20). A tapered portion (30) is tapered away from the circular opening. The tapered portion (30) includes a passage (32). A vibration sensor (34) is situated in the passage. A compressor and a method of sensing vibration adjacent a bearing in a compressor are also disclosed.
    Type: Application
    Filed: May 11, 2020
    Publication date: August 26, 2021
    Inventor: Vishnu M. Sishtla
  • Publication number: 20210254627
    Abstract: A method of controlling, by a controller for a compressor (200), pressure at plurality of magnetic motor thrust bearings (360, 370) for a motor (280) disposed within a housing (220) for the compressor (200), wherein the motor (280) and an impeller (270) are disposed on a compressor shaft (260) within the housing, the method including: monitoring current at each of the plurality of magnetic motor thrust bearings (360, 370), controlling a flow regulator (400) in a bypass loop (380) for the impeller (270) to decrease flow through the bypass loop when a first current in a first of the plurality of magnetic motor thrust bearings (360, 370) exceeds a second current in a second of the plurality of magnetic motor thrust bearings (360, 370), and controlling the flow regulator (400) to increase flow through the bypass loop (380) when the second current exceeds the first current.
    Type: Application
    Filed: September 6, 2019
    Publication date: August 19, 2021
    Inventor: Vishnu M. Sishtla
  • Patent number: 11067098
    Abstract: A compressor includes a diffuser section having a diffuser structure and a silencer. The silencer includes a silencer housing defining a cavity and a silencing pad disposed within the cavity, wherein an exposed surface of the silencing pad is arranged in contact with a portion of the diffuser structure.
    Type: Grant
    Filed: January 14, 2019
    Date of Patent: July 20, 2021
    Assignee: CARRIER CORPORATION
    Inventor: Vishnu M. Sishtla
  • Patent number: 11053950
    Abstract: A centrifugal compressor impeller (60; 160) has a hub (62; 162) having a gaspath surface (64; 164) extending from a leading end to a trailing end. A plurality of blades (70A, 70B; 170) extend from the hub gaspath surface and each have: a leading edge (72A, 72B; 172); a trailing edge (74A, 74B; 174); a first face (80A, 80B; 180); a second face (82A, 82B; 182); and a tip (78A, 78B; 178). A plurality of flow splitter segments (120, 122; 320, 322) extend between associated twos of the blades and each spaced from both the hub gaspath surface and the tips of the associated two blades.
    Type: Grant
    Filed: February 20, 2019
    Date of Patent: July 6, 2021
    Assignee: Carrier Corporation
    Inventors: Vishnu M. Sishtla, William T. Cousins
  • Publication number: 20210190093
    Abstract: The present invention provides a silencer, including: a silencer housing having an annular plate-like structure, with an annular mounting chamber formed therein; a silencing pad disposed in the mounting chamber; and a positioning portion disposed on the silencer housing and used for fastening the silencer housing. The silencer according to the embodiment of the present invention has an integrated structure, and can desirably avoid the problem of mounting unflatness in a separated structure. Moreover, the silencing pad therein is disposed to surround the entire silencer, which can provide a sound absorption and noise reduction effect more efficiently.
    Type: Application
    Filed: January 23, 2017
    Publication date: June 24, 2021
    Inventors: Vishnu M. Sishtla, Kai Deng, Zhanbo Du
  • Publication number: 20210189286
    Abstract: A compressor system includes a compressor including a compressor inlet, a compressor outlet, and a bearing assembly, the compressor configured to compress a heat transfer fluid. An additive dispenser is fluidly coupled to the compressor upstream of the bearing assembly. The additive dispenser is configured to controllably release a volume of an additive material into the heat transfer fluid, the additive material configured to lubricate the bearing assembly. A method of lubricating a bearing assembly of compressor includes locating a volume of additive material at an additive dispenser fluidly coupled to a compressor, dispensing a portion of the additive material into the flow of heat transfer fluid at a selected time, flowing the heat transfer fluid containing the additive material to a bearing assembly of the compressor, and lubricating the bearing assembly of the compressor with the additive material.
    Type: Application
    Filed: March 22, 2018
    Publication date: June 24, 2021
    Inventors: Zissis A. Dardas, Ulf J. Jonsson, Ying She, Zaffir A. Chaudhry, Vishnu M. Sishtla