Patent Description:
A heating, ventilation, air conditioning, and refrigeration (HVACR) system generally includes a compressor. Compressors, such as, but not limited to, centrifugal compressors, screw compressors, and scroll compressors, utilize bearings to support a spinning shaft. Various types of bearings can be considered, including hydrodynamic oil bearings and ball bearings, which require a lubricant system. In some circumstances, an oil-free operation is preferred. Such systems often utilize a gas bearing. Gas bearings do not utilize an oil-based lubricant, but gas leakages can reduce the capacity of the compressor. Gas bearings requires a clearance to prevent collision between the bearing and the object been supported. For example, the clearance required can be greater than <NUM> micrometers.

<CIT> describes a compressor having a foil bearing supporting the shaft.

<CIT> describes a turbomachine that includes a foil hydrodynamic fluid film thrust bearing.

This description relates generally to a bearing for a heating, ventilation, air conditioning, and refrigeration (HVACR) system. More specifically, this description relates to a gas bearing and seal assembly for a compressor in the HVACR system.

According to an embodiment, a gas bearing for a compressor includes a bearing portion and a sealing portion mounted to a bearing housing of the compressor via one or more dampers, and the sealing portion being fixedly connected to the bearing portion, and, a vent with an inlet in the bearing. The bearing portion has an inner radial surface for radially supporting a shaft of the compressor. The sealing portion has a sealing surface. The inlet of the vent disposed between the inner radial surface and the sealing surface. The sealing surface and a rotating surface form a path that extends along the sealing surface. The path extending from a pressurized volume of the compressor to the vent, and the pressurized volume containing a fluid.

In an embodiment, the rotating surface being an external surface of the rotating shaft.

In an embodiment, the rotating surface being a rotating side wall of an impeller of the compressor.

In an embodiment, the rotating surface being a rotating bottom of an impeller of the compressor.

In an embodiment, the one or more dampers include one or more of a spring, an O-ring, a squeeze film, and a wire mesh.

In an embodiment, the bearing portion and the sealing portion are fixedly connected by machining the sealing portion onto a material of the bearing portion.

In an embodiment, the bearing portion and the sealing portion are fixedly connected by one or more fasteners, by an adhesive, and/or by welding.

In an embodiment, one or more of the sealing portion and the sealing surface is made from steel, aluminum, ceramic, or graphite, or is coated with graphite.

In an embodiment, one or more of the rotating surface or the sealing surface includes a plurality of teeth, and the path being a tortuous path.

In an embodiment, the plurality of teeth is arranged along a rotational axis of the shaft over one or more of the shaft and a rotating side wall of the impeller.

In an embodiment, the plurality of teeth is arranged radially along a rotating base of the impeller.

A method for reducing a clearance requirement of a seal in a compressor includes mounting a bearing portion and a sealing portion to a bearing housing of the compressor via one or more dampers, fixedly connecting the sealing portion to the bearing portion, radially supporting a shaft of the compressor with an inner radial surface of the bearing portion, and venting the bearing. The sealing portion has a sealing surface. The sealing surface and a rotating surface form a path that extends along the sealing surface. The venting from an inlet of a vent is disposed between the inner radial surface and the sealing surface. The path extends from a pressurized volume of the compressor to the vent, and the pressurized volume contains a fluid.

In an embodiment, the rotating surface being one or more of an external surface of the rotating shaft, a rotating side wall of an impeller of the compressor, and a rotating bottom of an impeller of the compressor.

In an embodiment, the bearing portion and the sealing portion are fixedly connected by machining the sealing portion onto a material of the bearing portion or by one or more fasteners, by an adhesive, and/or by welding.

In an embodiment, the fluid includes a refrigerant fluidly connected to a refrigeration circuit including a condenser, an expander, an evaporator, and the compressor.

In an embodiment, the method further includes cooling one or more of the bearing and the bearing housing with a fluid leakage traveling through the vent in one or more of the bearing portion and in the bearing housing.

In an embodiment, the rotating surface and the sealing surface being arranged opposing each other.

By fixedly connecting a gas bearing for a compressor shaft and a labyrinth seal over the shaft and/or an impeller of the compressor, the clearance between a sealing surface of the seal and the shaft or the impeller can be reduced to the same or similar to a clearance between the gas bearing and the shaft. Reducing the clearance between the sealing surface and the shaft and/or impeller can reduce leakage and can increase capacity and efficiency of the compressor.

References are made to the accompanying drawings that form a part of this disclosure and which illustrate embodiments in which the systems and methods described in this specification can be practiced.

<FIG> is a schematic diagram of a refrigerant circuit <NUM>, according to an embodiment. The refrigerant circuit <NUM> generally includes a compressor <NUM>, a condenser <NUM>, an expander <NUM>, and an evaporator <NUM>.

The refrigerant circuit <NUM> is an example and can be modified to include additional components. For example, in an embodiment, the refrigerant circuit <NUM> can include other components such as, but not limited to, an economizer heat exchanger, one or more flow control devices, a receiver tank, a dryer, a suction-liquid heat exchanger, or the like.

The refrigerant circuit <NUM> can generally be applied in a variety of systems used to control an environmental condition (e.g., temperature, humidity, air quality, or the like) in a space (generally referred to as a conditioned space). Examples of such systems include, but are not limited to, HVACR systems, transport refrigeration systems, or the like. Examples of a conditioned space include, but not limited to, a portion of a home, building, an environmentally controlled container on a vehicle, ship, or vessel, or the like.

The compressor <NUM>, the condenser <NUM>, the expander <NUM>, and the evaporator <NUM> are fluidly connected via refrigerant lines <NUM>, <NUM>, <NUM>. In an embodiment, the refrigerant lines <NUM>, <NUM>, and <NUM> can alternatively be referred to as the refrigerant conduits <NUM>, <NUM>, and <NUM>, or the like.

In an embodiment, the refrigerant circuit <NUM> can be configured to be a cooling system (e.g., an air conditioning system) capable of operating in a cooling mode. In an embodiment, the refrigerant circuit <NUM> can be configured to be a heat pump system that can operate in both a cooling mode and a heating/defrost mode.

The refrigerant circuit <NUM> can operate according to generally known principles. The refrigerant circuit <NUM> can be configured to heat or cool a process fluid (e.g., a heat transfer medium or fluid such as, but not limited to, air, water, water glycol mixture, or the like), in which case the refrigerant circuit <NUM> may be generally representative of an air conditioner or heat pump.

In operation, the compressor <NUM> compresses a working fluid (e.g., a heat transfer fluid such as a refrigerant or the like) from a relatively lower pressure gas to a relatively higher-pressure gas. In an embodiment, the compressor <NUM> can be a centrifugal compressor. In an embodiment, the centrifugal compressor can operate at different speed ranges based on, for example, the compressor size and type. In an embodiment, the compressor <NUM> can be a screw compressor, a scroll compressor, or the like. In another embodiment, the compressor can include two or more stages of compression.

The relatively higher-pressure gas is also at a relatively higher temperature, which is discharged from the compressor <NUM> and flows through refrigerant line <NUM> to the condenser <NUM>. The working fluid flows through the condenser <NUM> and rejects heat to a process fluid (e.g., water, air, etc.), thereby cooling the working fluid. The cooled working fluid, which is now in a liquid or mostly liquid form, flows to the expander <NUM> via the refrigerant line <NUM>. The expander <NUM> reduces the pressure of the working fluid. As a result, a portion of the working fluid is converted to a gaseous form. The working fluid, which is now in a mixed liquid and gaseous form flows to the evaporator <NUM> via the remainder of refrigerant line <NUM>. The working fluid flows through the evaporator <NUM> and absorbs heat from a process fluid (e.g., water, air, etc.), heating the working fluid, and converting it to a gaseous form. The working fluid then returns to the compressor <NUM> via the refrigerant line <NUM>. The above-described process continues while the refrigerant circuit is operating, for example, in a cooling mode (e.g., while the compressor <NUM> is in operation).

<FIG> is a longitudinal cross-sectional view of a compressor <NUM>, according to an embodiment. In an embodiment, the compressor <NUM> is a centrifugal compressor having two stages. It will be appreciated that the compressor may be other compressor types, such as but not limited to a screw compressor, scroll compressor, and the like. It will be appreciated that the compressor <NUM> may not have two stages, and may have a single stage. In an embodiment, the centrifugal compressor <NUM> in <FIG> may be the compressor <NUM> employed in the heat transfer circuit <NUM> in <FIG> to compress a working fluid. The compressor <NUM> includes a housing <NUM>, a shaft <NUM>, a stator <NUM>, and impellers 140A, 140B. The housing <NUM> includes an inlet <NUM>, an outlet <NUM>, and endcaps 108A, 108B for the impellers 140A, 140B. The working fluid to be compressed enters the compressor <NUM> through the inlet <NUM> as shown by the dashed arrow f<NUM>. The compressed working fluid is discharged from the compressor <NUM> through the outlet <NUM> as shown by the dashed arrow f<NUM>. In an embodiment, the compressor <NUM> is an oil-free compressor.

The compressor <NUM> has a first compression stage S1 with the first impeller 140A and a second compression stage S2 with the second impeller 140B. The housing <NUM> includes an intermediate outlet <NUM> in the endcap 108A for the first stage S1, and an intermediate inlet <NUM> in the endcap 108B for the second stage S2. The working fluid flows from the first stage S1 to the second stage S2 through the intermediate outlet <NUM> and the intermediate inlet <NUM> as shown by the dashed line f<NUM>. In an embodiment, the dashed line f<NUM> may be a line that fluidly connects <NUM> and <NUM>. The dashed line f<NUM> is shown in <FIG> as extending outside of the housing <NUM>. However, it should be appreciated that the flow path shown by the dashed line f<NUM> may extend partially or completely within the housing <NUM> in an embodiment.

The stator <NUM> rotates the shaft <NUM> which rotates the impellers 140A, 140B. The working fluid is compressed in the first stage S1 and the second stage S2 by the rotating impellers 140A, 140B, respectively. A working fluid to be compressed is suctioning through the inlet <NUM>, compressed in the first stage S1, flows from the first stage S1 to the second stage S2, is further compressed in the second stage S2, and is then discharged through the outlet <NUM>. The working fluid discharged from the second stage S2 via the outlet <NUM> has a higher pressure than the working fluid discharged from the first stage S1 via the intermediate inlet <NUM>.

The compressor <NUM> includes bearings <NUM>, <NUM> for supporting the shaft <NUM> within the housing <NUM> while the shaft rotates. An inner radial surface <NUM> of the radial bearing <NUM> and/or an inner radial surface <NUM> of the bearing <NUM> radially support the shaft <NUM> while it rotates on the inner radial surfaces <NUM>, <NUM> of the radial bearings <NUM>, <NUM>. The radial bearings <NUM>, <NUM> can include bearing portions 38A, 38B and sealing portions 39A, 39B reducing a fluid leakage between the bearings <NUM>, <NUM> and a rotating surface of the compressor <NUM>. The bearing portion 38A, 38B can be a component or segment of the bearings <NUM>, <NUM> primarily for providing supports to the shaft <NUM>. The sealing portion 39A, 39B can be a component or segment of the bearings <NUM>, <NUM> primarily for reducing a fluid leakage. The bearing portions 38A, 38B can be radially surrounding the shaft <NUM> and providing support to shaft <NUM>. The bearing portion 38A, 38B and the sealing portion 39A, 39B can be separated components or segments of the bearings <NUM>, <NUM>. The bearing portion 38A, 38B can be radially surrounding and The rotating surface can be an external surface of the rotating shaft <NUM>, a rotating side wall of the impellers 140A, 140B, and/or a rotating bottom of the impellers 140A, 140B.

<FIG> is a cross-sectional view of the compressor <NUM> in <FIG>. <FIG> is a radial cross-section of an example of the gas bearing <NUM> along line <NUM>-<NUM> of <FIG>. The gas bearing <NUM> (shown in <FIG>) may have features same or similar to the gas bearing <NUM>.

An inner radial surface <NUM> of the bearing portion <NUM> provides support to the shaft <NUM> while it rotates. During operation of the compressor <NUM>, the shaft <NUM> rotates within the gas bearing <NUM> with a clearance <NUM> between the shaft <NUM> and the bearing portion <NUM>. For example, a layer of compressed gas is formed in the clearance <NUM> that levitates and supports the rotating shaft <NUM>. In an embodiment, the gas bearing <NUM> may be an aerostatic gas bearing that utilizes/distributes a flow of compressed gas into the clearance <NUM> to form the layer of compressed gas. In such an embodiment, the inner radial surface <NUM> of the bearing portions <NUM> supports the shaft <NUM> by providing the compressed gas into the clearance <NUM> that forms the layer of compressed gas and levitates the shaft <NUM>. In an embodiment, the gas bearing <NUM> may be a hydrodynamic bearing that utilizes structures on the inner radial surface <NUM> and/or the external surface of the shaft <NUM> (e.g., herringbone groves <NUM> shown in <FIG>, and the like) to form the layer of compressed gas in the clearance <NUM>. In such an embodiment, the inner radial surface <NUM> of the bearing portion <NUM> supports the shaft <NUM> by having structures or by providing a surface opposite to structures on the external surface of the shaft <NUM> (e.g., the inner radial surface being a surface opposite to the herringbone grooves <NUM> as shown in <FIG>, or the like) to form the layer of compressed gas in the clearance <NUM>.

A differential pressure is provided to a gas bearing, such as the gas bearings <NUM> (shown in <FIG>), <NUM> for radially supporting a rotating object therein. The rotating object can be the compressor shaft <NUM> when the compressor <NUM> is in operation. A high pressure and a low pressure can be provided to the gas bearing to provide the differential pressure. For example, the high pressure can be provided to a first end of the gas bearing and the low pressure can be provided to a second end of the gas bearing. For another example, the high pressure can be provided between the first and second end and the low pressure is provided at the first and second ends of the gas bearing. When the high pressure is provided between the two ends, the high pressure can be provided at a midpoint between the first and the second ends. One or more vent can be provided to maintain the low pressure. In an embodiment, the vent can be connected to a compressor inlet to maintain the low pressure.

In the illustrated embodiment, the gas bearing <NUM> having one or more dampers <NUM> includes a bearing portion <NUM> mounted to a bearing housing <NUM> via the one or more dampers <NUM>. The bearing housing <NUM> can be disposed radially outward with respect to the shaft <NUM>. At least some of the one or more dampers <NUM> are disposed between the bearing housing <NUM> and the bearing portion <NUM>.

In the illustrated embodiment, the gas bearing <NUM> includes one or more dampers <NUM>. In an embodiment, the one or more dampers <NUM> can include one or more O-rings, springs, squeeze films, and/or wire meshes. In an embodiment, the one or more dampers <NUM> can include a plurality of O-rings. In another embodiment, the one or more dampers <NUM> can include two O-rings. In one embodiment, the one or more dampers <NUM> can seal a gap between the bearing housing <NUM> and the bearing portion <NUM> preventing leakage of fluid through this gap. In another embodiment, a sealing feature (e.g., packing, a different O-ring, a labyrinth seal, or the like) may be disposed downstream from the gap to seal the gap.

<FIG> is a partial longitudinal cross-sectional view of a compressor <NUM>. For example, <FIG> can be a detailed view of the first stage S1 of the compressor <NUM> in <FIG>.

As illustrated in <FIG>, the compressor <NUM> includes the shaft <NUM>, the impeller 140A, and a gas bearing <NUM> having a bearing portion <NUM> and a sealing portion <NUM>. A clearance <NUM> is positioned between the bearing portion <NUM> and the shaft <NUM>. Due to scale, the clearances <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> in <FIG> are generally too small to be clearly illustrated in these views. For example, the clearances <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> in the illustrated embodiments are around <NUM> micrometers. Accordingly, the position of the clearances <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are generally indicated in <FIG>. Unless specified below, the compressor <NUM> can generally have features similar to the compressor <NUM>.

The gas bearing <NUM> includes the sealing portion <NUM> fixedly connected with the bearing portion <NUM>. The bearing portion <NUM> and the sealing portion <NUM> are compliant mounted to the bearing housing <NUM> with the plurality of dampers <NUM>. In the illustrated embodiment, the dampers <NUM> are O-rings. A sealing surface <NUM> of the sealing portion <NUM> faces a rotating surface <NUM> of the compressor <NUM>. The rotating surface <NUM> is a surface that rotates with the rotating shaft <NUM>. For example, the rotating surface <NUM> rotates relative to the bearing housing <NUM> and the housing <NUM> of the compressor <NUM>. The rotating surface <NUM> and the sealing surface <NUM> can be arranged opposing each other. In the illustrated embodiment of <FIG>, the rotating surface <NUM> is the rotating surface of the shaft <NUM> (e.g., the external radial surface of the shaft <NUM>). In other embodiments (e.g., see <FIG> and <FIG>), the rotating surface may be a rotating surface of the impeller 140A and the gas bearing <NUM> can be thrust bearings against the rotating surface of the impeller as discussed below.

The sealing surface <NUM> includes a plurality of teeth <NUM> that creates a tortuous path <NUM> between the sealing surface <NUM> and the rotating surface of the shaft <NUM>. The plurality of teeth <NUM> are in a fixed position relative to the inner radial surface <NUM> of the bearing portion <NUM> that supports the shaft <NUM> as it rotates. The plurality of teeth <NUM> can be arranged along the rotating outer surface of the shaft <NUM>. As shown in <FIG>, the plurality of teeth <NUM> can be arranged along a rotational axis A2 of the shaft <NUM>. Each of the teeth <NUM> extends around the circumference of the shaft <NUM>. In other embodiments, the plurality of teeth <NUM> may be additionally or alternatively arranged along a rotating surface of the impeller 140A (e.g., a side wall and/or a rotating bottom of the impeller) as discussed below (e.g., see <FIG> or <FIG>).

The tortuous path <NUM> reduces fluid leakage by having a series of fluid compressions and expansions when passing through the tortuous path <NUM>, which creates a higher pressure drop across the tortuous path <NUM> and reduces flowrate of the fluid leakage through the tortuous path <NUM>. This type of sealing provided by the teeth <NUM> can be referred to as a labyrinth seal. In particular, the tortuous path <NUM> reduces fluid leakage from a pressurized volume to a vent <NUM>. For example, the pressurized volume can be a pressurized chamber <NUM> of the compressor <NUM>, the outlet of the impeller 140A, or the like. The "pressurized" chamber/volume/fluid, etc. indicates a pressure at the chamber/volume/fluid, etc. being higher than a fluid pressure at the inlet before the compression (e.g., inlet of the compressor <NUM>, inlet of the impeller 140A, and the like) and does not indicate an absolute or relative fluid pressure over a reference fluid pressure, such as an ambient air pressure or vacuum. The pressurized chamber <NUM> can be a holding volume for a pressurized fluid after being discharged from the impeller and before the pressurized fluid being discharged from an outlet. For example, the impeller can be the impeller 140A or the impeller 140B, and the outlet can be the outlet <NUM> or outlet <NUM>, as shown in <FIG>.

By fixedly connecting the sealing portion <NUM> to the compliant mounted bearing portion <NUM> as shown in <FIG>, the clearance <NUM> between the sealing surface <NUM> and the shaft <NUM> can be reduced. For example, the clearance <NUM> between the sealing surface <NUM> and the shaft <NUM> can be reduced to be the same or similar to the clearance <NUM> (shown in <FIG>) between the bearing portion <NUM> and the shaft <NUM>. The clearance <NUM> would be larger if the sealing portion <NUM> is not fixedly connected to the bearing portion <NUM> when the bearing portion <NUM> is compliant mounted to the bearing housing <NUM>. A larger clearance would be used for a sealing portion that is not fixedly connected to the bearing portion to account for the general radial movements that occur to the shaft during operation (e.g., normal operation, surge, stall, or the like). The larger clearance to account for shaft movements can be an order of magnitude larger than the minimum clearance for the sealing portion <NUM> that is fixedly connected to the bearing portion <NUM> (e.g., the clearance <NUM> in <FIG>). By fixedly connecting the sealing portion <NUM> and the bearing portion <NUM>, the sealing portion <NUM> is stationary relative to the bearing portion <NUM>. The bearing portion <NUM> is compliant mounted and moves relative to the bearing housing <NUM> to maintain a clearance between the shaft <NUM> and the sealing portion <NUM>. For example, movement of the shaft <NUM> compresses the layer of compressed gas in the clearance <NUM> (shown in <FIG>) between the bearing portion <NUM> and the shaft <NUM>, which pushes and moves the bearing portion <NUM> by compression of the damper(s) <NUM>. As the sealing portion <NUM> is fixedly connected to the bearing portion <NUM>, the movement of the bearing portion <NUM> ensures a sufficient clearance between the sealing portion <NUM> and the shaft <NUM>. The reduced clearance between the sealing surface <NUM> and the shaft <NUM> can reduce leakage and increase capacity of the compressor <NUM>. The clearance between sealing surface <NUM> and the shaft <NUM> can be the radial distance between the teeth <NUM> and the exterior surface of the shaft <NUM>. In an embodiment, the clearance between the sealing surface <NUM> and the shaft <NUM> is less than <NUM> micrometers. In an embodiment, the clearance between the sealing surface <NUM> and the shaft <NUM> is less than <NUM> micrometers. In an embodiment, the clearance between the sealing surface <NUM> and the shaft <NUM> is less than <NUM> micrometers.

The bearing <NUM> can include the vent <NUM> as shown in <FIG>. The vent <NUM> allows the fluid leakage from the outlet of the impeller 140A to be released through the bearing <NUM>. As illustrated in <FIG>, the vent <NUM> passes through the bearing housing <NUM> and the bearing <NUM>. The vent <NUM> extends through the bearing <NUM> to its internal aperture through which the shaft <NUM> extends. The fluid leakage can further provide a cooling effect in passing through the bearing housing <NUM> and the bearing <NUM>. The vent <NUM> includes a vent inlet <NUM> disposed between the bearing portion <NUM> and the sealing portion <NUM> of the bearing <NUM>. As illustrated in <FIG>, the vent inlet <NUM> is disposed between the sealing surface <NUM> and the inner radial surface <NUM> of the bearing portion <NUM>.

As shown in the illustrated embodiment of <FIG>, the sealing portion <NUM> and the bearing portion <NUM> are fixedly connected by being integrally formed from a same piece of material. For example, the sealing portion <NUM> can be machined into the material of bearing portion <NUM>. The material for the sealing portion <NUM> and/or the bearing portion <NUM> can be made from steel, aluminum, ceramic, or graphite and/or being coated with graphite.

<FIG> is a partial longitudinal cross-sectional view of a compressor <NUM>, according to another embodiment. As illustrated in <FIG>, the example of the compressor <NUM> includes the shaft <NUM>, the impeller 140A, the gas bearing <NUM> that includes a bearing portion <NUM> and a sealing portion <NUM>. The gas bearing <NUM> is compliant mounted to the bearing housing <NUM> via one or more dampers <NUM>. The sealing portion <NUM> and the bearing portion <NUM> are fixedly connected by fixedly attaching the sealing portion <NUM> and the bearing portion <NUM>. For example, the sealing portion <NUM> and the bearing portion <NUM> can be fixedly connected or fixedly attached by one or more adhesives, by one or more fasteners, and/or by welding. Unless specified below, the compressor <NUM> can generally have features similar to the compressor <NUM> or <NUM>. Rather than forming the sealing portion <NUM> and the bearing portion <NUM> from a same piece of material as illustrated in <FIG>, the sealing portion <NUM> and the bearing portion <NUM> of the gas bearing <NUM> in <FIG> are fixedly connected or attached from assembling two or more components.

<FIG> is a partial longitudinal cross-sectional view of a compressor <NUM>, according to yet another embodiment. As illustrated in <FIG>, the example of the compressor <NUM> includes the shaft <NUM>, the impeller 140B, a gas bearing <NUM> that includes a bearing portion <NUM> and a sealing portion <NUM>. The gas bearing <NUM> is compliant mounted to the bearing housing <NUM> via one or more dampers <NUM>. In an embodiment, the damper(s) <NUM> may a similar form/configuration as discussed above for the dampers <NUM> in <FIG> and/or the dampers <NUM> in <FIG>. Unless specified below, the compressor <NUM> can generally have features similar to the compressor <NUM>, <NUM>, or <NUM>.

According to the illustrated embodiment, the bearing portion <NUM> and the sealing portion <NUM> are compliant mounted to the bearing housing <NUM> with the damper(s) <NUM>. The gas bearing <NUM> can include a sealing portion <NUM> fixedly connected with the bearing portion <NUM>. A sealing surface <NUM> of the sealing portion <NUM> includes a plurality of teeth <NUM> creating a tortuous path <NUM> between the sealing surface and the impeller 140B. The plurality of teeth <NUM> can be arranged along the impeller 140B and/or radially surrounding the impeller 140B. In an embodiment, the plurality of teeth <NUM> is positioned against a rotating side wall <NUM> of the impeller 140B. In another embodiment, the plurality of teeth <NUM> is positioned against a rotating bottom <NUM> of the impeller 140B. The rotating bottom <NUM> spins around a rotational axis A2 (shown in <FIG>) of the shaft <NUM>.

The gas bearing <NUM> includes a vent <NUM>. The tortuous path <NUM> extends to the vent <NUM>. The tortuous path <NUM> reduces fluid leakage by having a series of compressions and expansions when passing through the tortuous path <NUM>, which creates a higher pressure drop across the tortuous path <NUM> and reduces flowrate of the fluid leakage through the tortuous path <NUM>. The vent <NUM> has a vent inlet disposed between the bearing portion <NUM> and the sealing portion <NUM> of the bearing <NUM> (e.g., along the axial direction of the shaft <NUM>). The vent <NUM> extends through the bearing <NUM> to its internal aperture through which the shaft <NUM> extends. In particular, as shown in <FIG>, the vent <NUM> extends to the portion of the internal aperture in which the impeller 140B is disposed. The vent inlet is disposed between the sealing surface <NUM> of the sealing portion and the inner radial surface of the bearing portion <NUM>. As shown in the illustrated embodiment, the vent <NUM> passes through the bearing housing <NUM>.

According to the illustrated embodiment, the sealing portion <NUM> and the bearing portion <NUM> can be fixedly connected by forming from a same piece of material. According to another embodiment, the sealing portion <NUM> can be machined into the bearing portion <NUM>. According to yet another embodiment, the sealing portion <NUM> and/or the bearing portion <NUM> can be made from steel, aluminum, ceramic, or graphite and/or being coated with graphite.

Rather than forming the sealing portion <NUM> around the shaft <NUM> as illustrated in <FIG>, the sealing portion <NUM> in <FIG> is formed around the rotating side wall <NUM> or the rotating bottom <NUM> of the impeller 140B.

<FIG> is a partial longitudinal cross-sectional view of the compressor <NUM>, according to yet another embodiment. As illustrated in <FIG>, the example of the compressor <NUM> includes the shaft <NUM>, the impeller 140B, a gas bearing <NUM> that includes a bearing portion <NUM> and a sealing portion <NUM>. The bearing portion <NUM> supports the shaft <NUM> when the compressor <NUM> is in operation. Unless specified below, the compressor <NUM> can generally have features similar to the compressor <NUM>, <NUM>, <NUM>, or <NUM>.

The bearing portion <NUM> and the sealing portion <NUM> are compliant mounted to the bearing housing <NUM> with one or more dampers <NUM>. In an embodiment, the damper(s) <NUM> may be a similar form/configuration as discussed above for the dampers <NUM> in <FIG> and/or the dampers <NUM> in <FIG>. The gas bearing <NUM> can include a sealing portion <NUM> fixedly connected with the bearing portion <NUM>. A sealing surface <NUM> of the sealing portion <NUM> includes a plurality of teeth <NUM> creating a tortuous path <NUM> between the sealing surface <NUM> and the impeller 140B. The tortuous path <NUM> reduces fluid leakage by having a series of compressions and expansions when passing through the tortuous path <NUM>, which creates a higher pressure drop across the tortuous path <NUM> and reduces flowrate of the fluid leakage through the tortuous path <NUM>. For example, the pressurized volume <NUM> can be the pressurized chamber of the compressor <NUM>. In an embodiment, the plurality of teeth <NUM> and the impeller 140B can form one or more labyrinth seal.

In an embodiment, the plurality of teeth <NUM> is positioned against a rotating side wall <NUM> of the impeller 140B. In another embodiment, a plurality of teeth is positioned against a rotating bottom <NUM> of the impeller 140B alternatively or additionally to the plurality of teeth <NUM> positioned against the rotating side wall <NUM>.

The bearing <NUM> can includes a vent <NUM> that allows the fluid leakage to be released from the bearing <NUM>. The vent <NUM> can pass through the bearing portion <NUM>. The fluid leakage can further provide cooling effect passing through the bearing <NUM>. Compared to the bearing <NUM> of <FIG>, the bearing <NUM> of <FIG> can include a bearing housing <NUM> thicker than the bearing housing <NUM>. The thicker bearing housing <NUM> allows the vent <NUM> to be positioned in the bearing housing <NUM>.

According to one embodiment, the plurality of teeth can be included on the rotating surface of the shaft or the impellers opposing the sealing surface of the sealing portion of the bearing, instead of being on the sealing surface of the sealing portion. For example, the plurality of teeth <NUM>, <NUM>, <NUM>, and <NUM> can be included on the rotating surface of the shaft or the impellers (e.g., the rotating surface <NUM> of the shaft <NUM> in <FIG>, the rotating side wall <NUM>, the rotating bottom <NUM>, and the like). For example, teeth on the rotating surface <NUM> of the shaft <NUM> can be recessed into the rotating surface <NUM> to create the rotating path <NUM>.

<FIG> is a partial longitudinal cross-sectional view of a compressor <NUM>, according to yet another embodiment. As illustrated in <FIG>, the example of the compressor <NUM> includes the shaft <NUM>, the impeller 140A, a gas bearing <NUM> that includes a bearing portion <NUM> and a sealing portion <NUM>. The gas bearing <NUM> is compliant mounted to the bearing housing <NUM> via one or more dampers <NUM>. A clearance <NUM> is positioned between the bearing portion <NUM> and the shaft <NUM>. In an embodiment, the damper(s) <NUM> may a similar form/configuration as discussed above for the dampers <NUM> in <FIG> and/or the dampers <NUM> in <FIG>. Unless specified below, the compressor <NUM> can generally have features similar to the compressor <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

The gas bearing <NUM> includes the sealing portion <NUM> fixedly connected with the bearing portion <NUM>. The bearing portion <NUM> and the sealing portion <NUM> are compliant mounted to the bearing housing <NUM> with the plurality of dampers <NUM>. In the illustrated embodiment, the dampers <NUM> are O-rings. A sealing surface <NUM> of the sealing portion <NUM> faces a rotating surface <NUM> of the compressor <NUM>. The rotating surface <NUM> is a surface that is rotated by the rotating shaft <NUM>. For example, the rotating surface <NUM> rotates relative to the bearing housing <NUM> and a housing the compressor <NUM>. The rotating surface <NUM> and the sealing surface <NUM> can be arranged opposing each other. In the illustrated embodiment, the rotating surface <NUM> is the rotating surface of the shaft <NUM> (e.g., the external radial surface of the shaft <NUM>). A vent <NUM> is disposed between the bearing portion <NUM> and the sealing portion <NUM>. Specifically, an inlet of the vent <NUM> disposed between the sealing surface <NUM> of the sealing portion <NUM> and an inner radial surface <NUM> of the bearing portion <NUM>.

A path <NUM> is created between the sealing surface <NUM> and the rotating surface <NUM> of the shaft <NUM>. The sealing surface <NUM> is in a fixed position relative to the inner radial surface of the bearing portion <NUM> that supports the shaft <NUM> as it rotates. Rather than forming, for example, the tortuous path <NUM> as shown in <FIG>, the embodiment of <FIG> reduces fluid leakage by creating a path <NUM> between the sealing surface <NUM> and the rotating surface <NUM> that oppose each other across a clearance <NUM>. The sealing surface <NUM> faces the rotating surface <NUM>. In an embodiment, the clearance between the sealing surface <NUM> and the shaft <NUM> is less than <NUM> micrometers. In an embodiment, the clearance <NUM> between the sealing surface <NUM> and the shaft <NUM> is less than <NUM> micrometers. In an embodiment, the clearance <NUM> between the sealing surface <NUM> and the shaft <NUM> is less than <NUM> micrometers.

In an embodiment, the bearing portion <NUM> can be positioned opposing a levitating surface <NUM> of the shaft <NUM>. The levitating surface <NUM> is on a portion of the external radial surface of the shaft <NUM> opposing the inner radial surface <NUM> of the bearing portion <NUM>. When the compressor <NUM> is in operation, the shaft <NUM> rotates and creates a compressed fluid layer between the bearing portion <NUM> and the levitating surface <NUM> supporting the shaft <NUM> in place. For example, the levitating surface <NUM> can include herringbone grooves <NUM> to create the compress fluid layer supporting the shaft <NUM>. In another example, a compressed fluid source provides compressed fluid to the body of the bearing portion <NUM> via a compressed fluid conduit. The compressed fluid is provided to the body of the bearing portion <NUM> and dispersed across the bearing portion <NUM> (e.g., the bearing <NUM> configured to have the compressed fluid dispersed from the inner radial surface <NUM> of the bearing portion <NUM> into the clearance <NUM>). The dispersion can be achieved, for example, by including a porous material nearing the inner surface of the bearing portion <NUM> and conducting the compressed fluid from the compressed fluid conduit across the inner surface of the bearing portion <NUM>.

Rather than forming a tortuous path between the sealing portion and rotating surface as in, for example, <FIG>, the illustrated embodiment in <FIG> includes a path <NUM> reducing fluid leakage by having the sealing surface <NUM> and the rotating surface <NUM> opposing each other with a small clearance to introduce back pressure and reduce a flowrate of fluid through the path <NUM>. For example, the sealing portion <NUM> can be a bushing seal. It is appreciated that the sealing portion can be formed from a combination of seals as shown and described in <FIG>.

<FIG> is a flowchart of a method <NUM> for reducing a clearance requirement of a seal in a compressor, according to an embodiment. In an embodiment, the method <NUM> may be employed by the compressor <NUM>, the compressor <NUM>, the compressor <NUM>, the compressor <NUM>, the compressor <NUM>, or the compressor <NUM>. The method <NUM> starts at <NUM>.

At <NUM>, a bearing portion (e.g., bearing portion <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and a sealing portion (e.g., sealing portion <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) are mounted to a bearing housing (e.g., bearing housing <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) of a compressor via one or more dampers (e.g., dampers <NUM>, <NUM>, <NUM>, <NUM>). The method <NUM> then proceeds to <NUM>.

The method <NUM> further includes fixedly connecting the sealing portion to the bearing portion (e.g., bearing portion <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) <NUM>, radially supporting a shaft of the compressor (e.g., shaft <NUM>) with an inner radial surface of the bearing portion <NUM>, and cooling one or more of the bearing and the bearing housing with a fluid leakage traveling through the vent (e.g., vent <NUM>, <NUM>, <NUM>, <NUM>) in one or more of the bearing portion and in the bearing housing <NUM>.

Claim 1:
A gas bearing (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) for a compressor (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), comprising:
a bearing portion (<NUM>, 38a, 38b, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and a sealing portion (39a, 39b, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) mounted to a bearing housing (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) for the compressor via one or more dampers (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), and the sealing portion being fixedly connected to the bearing portion; and
a vent (<NUM>, <NUM>, <NUM>, <NUM>) with an inlet (<NUM>) in the bearing, wherein
the bearing portion has an inner radial surface (<NUM>, <NUM>, <NUM>, <NUM>) for radially supporting a shaft (<NUM>) of the compressor,
the sealing portion has a sealing surface (<NUM>, <NUM>, <NUM>, <NUM>),
the inlet of the vent is disposed between the inner radial surface and the sealing surface,
the sealing surface and a rotating surface (<NUM>, <NUM>) form a path (<NUM>, <NUM>, <NUM>, <NUM>) that extends along the sealing surface,
the path configured to extend from a pressurized volume (<NUM>) of the compressor containing a fluid to the vent.