Compressor assembly including flow restriction valve

Abstract

The present invention relates to a compressor assembly including a flow restriction valve. Specifically, an illustrative example embodiment of the compressor assembly includes a compressor housing having a suction inlet and a discharge outlet. During a first operating condition, the flow restriction valve allows unrestricted fluid flow in a first direction through the suction inlet into the housing and out of the discharge outlet. During a second operating condition, the flow restriction valve allows restricted fluid flow in an opposite, second direction through the discharge outlet into the housing.

Description

Background Art

[0001] Compressors have a variety of uses, including, for example, refrigerant circuits for refrigeration or air conditioning. A variety of compressor designs are available. One type of compressor includes magnetic bearings (sometimes also called magnetic levitation bearings) to facilitate the rotation of rotating components of the compressor, such as a motor shaft. Magnetic bearings can contribute to longer compressor life and reduced maintenance because they provide contactless support for rotating components.

[0002] One disadvantage of magnetic bearings is their limited ability to withstand certain aerodynamic forces. For example, during surge or uncontrolled shutdown, unstable aerodynamic forces acting on compressor components can cause the magnetic bearings to effectively lose control of the motor shaft's position, leading to contact with a touchdown bearing. When this happens, bearing life is shortened. In addition, when motor shaft control is lost, a bearing alarm is triggered, requiring a manual reset. Summary of the Invention

[0003] An illustrative example embodiment of a compressor assembly includes a compressor housing having a suction inlet and a discharge outlet. During a first operating condition, a flow restriction valve allows unrestricted fluid flow in a first direction through the suction inlet into the housing and out of the discharge outlet. During a second operating condition, the flow restriction valve allows restricted fluid flow in an opposite, second direction through the discharge outlet into the housing.

[0004] In addition to one or more of the above features, or as an alternative, the flow limiting valve includes a fluid passage and a blocking member configured to be in a first position during a first operating condition and in a second position during a second operating condition; the fluid blocking member allows unrestricted flow through the fluid passage in the first position; and the fluid blocking member partially blocks the passage in the second position to allow restricted fluid flow through the passage during the second operating condition.

[0005] Additionally or alternatively to one or more of the above features, the fluid barrier member includes at least one aperture through which some fluid may flow past the barrier member and through the passageway when the fluid barrier member is in the second position.

[0006] In addition to or as an alternative to one or more of the features described above, the fluid blocking member comprises flaps.

[0007] In addition to or instead of one or more of the above features, the petal includes a disc; the disc is supported by an arm adjacent the disc; and the at least one aperture is aligned with the arm such that at least some fluid flowing through the at least one aperture encounters the arm before continuing through the channel in a second direction.

[0008] In addition to or alternatively to one or more of the above features, the channel includes a surface that at least partially receives the fluid barrier member relative to it in the second position; at least one of the surface or the fluid barrier member includes a feature that prevents a complete seal from being established between the surface and the fluid barrier member in the second position.

[0009] Additionally or alternatively to one or more of the above features, the restricted fluid flow is between 5% and 15% of the unrestricted fluid flow.

[0010] Additionally or alternatively to one or more of the above features, the restricted fluid flow is between 5% and 10% of the unrestricted fluid flow.

[0011] In addition to or in lieu of one or more of the above features, the restricted fluid flow rate is approximately 12.5% ​​of the unrestricted fluid flow rate.

[0012] Additionally or alternatively to one or more of the above features, the restricted fluid flow is less than 10% of the unrestricted fluid flow.

[0013] In addition to or instead of one or more of the above features, the compressor assembly includes at least one rotating component within the housing; and at least one magnetic bearing supporting the at least one rotating component in a manner that facilitates rotation of the at least one rotating component.

[0014] An illustrative example embodiment of a method of controlling fluid flow through a compressor casing having a suction inlet and a discharge outlet includes allowing unrestricted fluid flow in a first direction into the casing through the suction inlet and out of the discharge outlet during a first operating condition; and allowing restricted fluid flow in an opposite, second direction into the casing through the discharge outlet under a second operating condition.

[0015] In addition to or instead of one or more of the above features, the compressor housing contains a rotating compressor component and a magnetic bearing that facilitates rotation of the rotating compressor component.

[0016] Additionally or alternatively to one or more of the above features, a method includes placing a restrictor valve in a position to control fluid flow through an exhaust outlet; opening the restrictor valve during a first operating condition; and at least partially closing the restrictor valve during a second condition.

[0017] Additionally or alternatively to one or more of the above features, the restricted fluid flow is between 5% and 10% of the unrestricted fluid flow.

[0018] The various features and advantages of at least one disclosed example embodiment will become apparent to those skilled in the art from the following detailed description.The drawings that accompany the detailed description can be briefly described as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 An example embodiment of a refrigeration circuit including a flow restriction valve is schematically illustrated.

[0020] Figure 2 Example configurations of selected portions of a flow restrictor valve are shown.

[0021] Figure 3 Another example configuration of selected portions of a flow restrictor valve is shown. DETAILED DESCRIPTION

[0022] Figure 1 A refrigeration circuit 20 is schematically shown. A compressor 22 includes a housing having a suction inlet 24 and a discharge outlet 26. The compressor 22 includes a known rotating component driven by a motor 28. At least one magnetic bearing 30 is associated with the rotating component, such as a shaft of the motor 28, to facilitate rotation within the housing of the compressor 22.

[0023] Refrigeration circuit 20 includes a condenser 22, an expansion valve 34, and a chiller 36. Compressor 22, condenser 32, expansion valve 34, and chiller 36 each operate in a generally known manner.

[0024] The flow restriction valve 40 is configured to allow unrestricted fluid flow through the suction inlet 24 into the casing of the compressor 22 and out of the discharge outlet 26 in a first direction under a first operating condition, which corresponds to normal or desired operation of the refrigeration circuit 20. In other words, the flow restriction valve 40 does not impede the flow of fluid, such as refrigerant, within the circuit 20 under the first operating condition. The flow restriction valve is further configured to allow restricted flow into the compressor 22 through the discharge outlet 26 in an opposite, second direction under a different, second operating condition.

[0025] An example of this second operating condition occurs immediately after compressor 22 shuts down. For example, immediately after some types of compressors shut down, there is a significant pressure differential between cooler 36 and condenser 32. Circuit 20 will tend to equalize, and the higher pressure in condenser 32 will force fluid back into cooler 36, where it is at a lower pressure. Because compressor 22 is located between condenser 32 and cooler 36, fluid will flow into discharge outlet 26 and through compressor 22. Restrictor valve 40 controls this fluid flow, allowing only a limited amount of fluid to flow through discharge outlet 26 into the compressor 22 housing under these conditions. Refrigeration circuit 20 includes a hot gas bypass path 42 through which fluid can flow when the pressures in condenser 32 and cooler 36 are equal. Valve 43 controls whether fluid can flow through bypass path 42. Valve 43 remains closed during normal operation of refrigeration circuit 20. Valve 43 opens in situations that could cause undesirable backflow through compressor 22.

[0026] The restrictor valve 40 remains fully open during the first operating condition to allow unrestricted fluid flow into the suction inlet 24 and out of the discharge outlet 26. The restrictor valve 40 allows some restricted flow into the discharge outlet 26 and through the compressor 22 during the second operating condition. From one perspective, it may be desirable to completely shut off this fluid flow during shutdown; however, a valve that does so introduces other potential complications.

[0027] The flow restrictor valve 40 operates like a modified check valve. A typical check valve only allows flow in only one direction. The flow restrictor valve 40 allows unrestricted flow in one direction and at least some restricted flow in the opposite direction.

[0028] For example, if the restrictor valve 40 is designed to completely close or prevent flow through the valve in one of two directions, this could result in rapid changes in flow through the compressor 22 during surge. Such changes are undesirable because they exert shock forces within the compressor 22, which tend to cause the magnetic bearings 30 to lose control of the position of at least the shaft of the motor 28. Allowing some restricted flow through the restrictor valve 40 inhibits or reduces such rapid changes in fluid flow through the compressor 22.

[0029] Thus, the flow restriction valve 40 allows at least some flow in each of the two directions. Controlling the amount of flow in the second direction into the discharge outlet 26 of the compressor 26 when the circuit 20 is balanced avoids an amount of flow in the second direction that would otherwise cause the rotating components of the compressor 22 to reverse rotate at a speed that could cause the magnetic bearings 30 to lose control of the position of the shaft of the motor 28. Some fluid may flow in the second direction into the discharge outlet 26 and through the compressor, even at a level that causes reverse rotation of the rotating components in the compressor 22, as long as such flow is insufficient to introduce sufficient aerodynamic forces to overcome the position control provided by the magnetic bearings 30.

[0030] Restrictor valve 40 strikes a balance between the need to avoid surge forces within compressor 22 under some conditions (eg, surge) and the need to prevent significant backflow through compressor 22 under other conditions. Restrictor valve 40 may be considered a modified or partial check valve.

[0031] like Figure 2 and 3 As shown in FIG, in some embodiments, the flow restrictor valve 40 includes a fluid blocking member 44, such as a flap or disc, that moves between an open position and a flow restricting position. Figure 24. An example fluid blocking member 44 is shown in FIG. In this example, the fluid blocking member 44 comprises a disk that selectively moves to a position to close the passage through the restrictor valve 40. The disk 44 includes at least one opening or aperture 46 therethrough. Even when the disk 44 is in the closed position, some fluid can flow through such aperture 46, past the disk 44, and through the valve 40 toward the drain outlet 26.

[0032] exist Figure 2 In the example embodiment, a plurality of holes 46 are positioned relative to a support arm 48 that supports the disc 44 in the open and closed positions, such that the support arm 48 is in the path of the fluid flowing through the holes 46. In other words, in this example embodiment, at least some of the fluid permitted to flow through the openings 46 encounters the support arm 48. The size of the holes, combined with the overlap of the support arm 48, provides a desired restricted flow rate through the valve 40 in the second direction. The holes 46 also provide a damping effect during surge, compared to the effect that would occur if the disc 44 did not include any holes 46.

[0033] Figure 3 Another example arrangement of a disc-shaped fluid blocking member 44 and a surface 50 opposite thereto for receiving disc 44 in a closed position is schematically shown. In this example, at least one of disc 44 or surface 50 includes at least one feature 52 that prevents disc 44 from establishing a complete seal along surface 50 when disc 44 is in the closed position. When disc 44 is in the closed position, at least some restricted fluid flow is permitted through passage 54 because feature 52 maintains some spacing between corresponding portions of surface 50 and an adjacent face of disc 44.

[0034] Regardless of whether the fluid blocking member 44 includes at least one aperture or is prevented from establishing a seal relative to flow in the second direction, the restricted fluid flow is a relatively low percentage of flow compared to the fluid flow allowed through the restrictor valve 40 when the valve is fully open under the first operating condition. In some example embodiments, a restricted flow of up to 15% of the flow when the valve is open is useful. Restricting the flow to between 5% and 15% of the unrestricted fluid flow under the second operating condition, such as directly after shutdown, accommodates some fluid flow through the compressor 22 while avoiding reverse rotation at an undesirable high speed. In some embodiments, based on the configuration of the restrictor valve 40, the restricted fluid flow is maintained between 5% and 10% of the unrestricted fluid flow. In one example embodiment, the restricted fluid flow is approximately 12.5% ​​of the unrestricted fluid flow. Some embodiments include maintaining the restricted fluid flow at less than 10% of the unrestricted fluid flow, as long as at least some flow is allowed.

[0035] The manner in which the flow restriction valve 40 allows at least some restricted flow in both opposite directions when the valve 40 transitions between the closed position and the open position reduces the severity of flow interruptions through the valve 40 and the compressor 22 during surge. This improves the stability of the magnetic bearing 30 during surge conditions. For example, moderating the rate at which refrigerant can flow back through the compressor 22 after an unpowered shutdown reduces the maximum reverse rotational speed of the rotating components of the compressor 22. Maintaining the reverse rotational speed within desired limits avoids conditions that would overcome the ability of the magnetic bearings to maintain control of the position of the shaft of the motor 28.

[0036] Controlling the flow of fluid through the compressor in a manner consistent with the above can increase bearing life and reduce the frequency of compressor maintenance, both of which contribute to longer-lasting and more reliable compressor performance.

[0037] The foregoing description is illustrative rather than restrictive in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art without departing from the essence of the invention. The scope of legal protection afforded this invention can only be determined by studying the following claims.

Claims

1. A compressor assembly comprising: a compressor housing having a first end and a second end opposite the first end, the compressor housing including a suction inlet at the first end and a discharge outlet at the second end; a compressor positioned within the compressor housing and comprising: at least one rotating component positioned within the compressor housing between the suction inlet and the discharge outlet; and at least one magnetic bearing supporting the at least one rotating component in a manner that facilitates rotation of the at least one rotating component; and a flow restriction valve configured to allow unrestricted fluid flow in a first direction through the suction inlet into the housing and out of the discharge outlet during a first operating condition, and to allow restricted fluid flow in an opposite, second direction through the discharge outlet into the housing during a second operating condition, wherein the flow restriction valve is positioned within the refrigeration circuit between the discharge outlet from the compressor housing and a condenser, wherein the first operating condition corresponds to normal or desired operation of the refrigeration circuit, wherein the flow restriction valve is configured to allow unrestricted fluid flow in the first direction through the suction inlet into the compressor housing and out of the discharge outlet; wherein the second operating condition occurs immediately after shutdown of the compressor, and wherein, during the second operating condition, the flow restriction valve is configured to allow only a restricted amount of fluid flow into the compressor housing of the compressor through the discharge outlet; wherein the restrictor valve is external to the compressor housing and immediately downstream of the discharge outlet when operating under the first operating condition; wherein, when operating under the first operating condition, the condenser is immediately downstream of the flow restriction valve, and wherein, when operating under the second operating condition, the flow restriction valve is immediately upstream of the discharge outlet; and wherein the refrigeration circuit includes a bypass path through which the fluid may flow when the pressures in the condenser and the cooler are equal, and wherein the bypass path includes a valve configured to control whether the fluid may flow through the bypass path, wherein the valve remains closed during the first operating condition, and wherein the valve opens during conditions that may cause undesirable backflow through the compressor during the second operating condition.

2. The compressor assembly according to claim 1, wherein The flow restrictor valve includes a fluid passage and a fluid barrier member configured to be in a first position during the first operating condition and in a second position during the second operating condition; the fluid blocking member allowing unrestricted flow through the fluid passage in the first position; and The fluid blocking member partially blocks the passageway in the second position to allow restricted fluid flow through the passageway during the second operating condition.

3. The compressor assembly of claim 2, wherein The fluid barrier member includes at least one aperture through which some fluid may flow past the barrier member and through the passageway when the fluid barrier member is in the second position.

4. The compressor assembly according to claim 3, wherein: The fluid blocking member includes petals.

5. The compressor assembly of claim 4, wherein The petal includes a disc; The tray is supported by an arm proximate the tray; and The at least one aperture is aligned with the arm such that at least some fluid flowing through the at least one aperture encounters the arm before continuing through the channel in a second direction.

6. The compressor assembly of claim 2, wherein the channel comprising a surface relative thereto at least partially receiving the fluid blocking member in the second position; and At least one of the surface or the fluid blocking member includes features that prevent a complete seal from being established between the surface and the fluid blocking member in the second position.

7. The compressor assembly of claim 1, wherein: The restricted fluid flow rate is between 5% and 15% of the unrestricted fluid flow rate.

8. The compressor assembly according to claim 7, wherein: The restricted fluid flow rate is between 5% and 10% of the unrestricted fluid flow rate.

9. The compressor assembly according to claim 7, wherein: The restricted fluid flow rate is approximately 12.5% ​​of the unrestricted fluid flow rate.

10. The compressor assembly of claim 1, wherein: The restricted fluid flow is less than 10% of the unrestricted fluid flow.

11. A method of controlling fluid flow through a compressor housing having a first end and a second end opposite the first end, the compressor housing having a suction inlet at the first end and a discharge outlet at the second end, the method comprising: Providing a refrigeration circuit comprising at least a condenser, an expansion valve, a cooler and a compressor; positioning the compressor within the compressor housing, the compressor comprising: at least one rotating component positioned within the compressor housing between the suction inlet and the discharge outlet; and at least one magnetic bearing supporting the at least one rotating component in a manner to facilitate rotation of the at least one rotating component; placing a flow restriction valve in a position to control fluid flow through the discharge outlet, wherein the position is within the refrigeration circuit between the discharge outlet from the compressor housing and the condenser; allowing unrestricted fluid flow in a first direction during a first operating condition, wherein the first operating condition corresponds to normal or desired operation of the refrigeration circuit, wherein the restrictor valve is configured to allow unrestricted fluid flow in the first direction through the suction inlet into the compressor housing and out of the discharge outlet; allowing restricted fluid flow in an opposite, second direction during a second operating condition, wherein the second operating condition occurs immediately after shutdown of the compressor, and wherein, during the second operating condition, the restrictor valve is configured to allow only a restricted amount of fluid flow into the compressor housing of the compressor through the discharge outlet; wherein the restrictor valve is external to the compressor housing and immediately downstream of the discharge outlet when operating under the first operating condition; wherein, when operating under the first operating condition, the condenser is immediately downstream of the flow restriction valve, and wherein, when operating under the second operating condition, the flow restriction valve is immediately upstream of the discharge outlet, and wherein, when operating under the first operating condition, the discharge outlet discharges fluid from the compressor housing directly into the refrigeration circuit; and wherein the refrigeration circuit includes a bypass path through which the fluid can flow when the pressures in the condenser and the cooler are equal, and wherein the bypass path includes a valve configured to control whether the fluid can flow through the bypass path, wherein the valve remains closed during the first operating condition, and wherein the valve opens during conditions that may cause undesirable backflow through the compressor during the second operating condition, and wherein the bypass path has a first connection to the refrigeration circuit at a location between the flow restriction valve and the condenser, and has a second connection to the refrigeration circuit at a location between the cooler and the suction inlet.

12. The method according to claim 11, comprising: opening the restrictor valve during the first operating condition; and The restrictor valve is at least partially closed during the second operating condition.

13. The method according to claim 11, wherein The restricted fluid flow rate is between 5% and 10% of the unrestricted fluid flow rate.

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