Compact variable volume index valve for screw compressors

Abstract

Provided is a screw compressor and a compact variable volume indexing valve therefor, the compact variable volume indexing valve including a linear valve member disposed adjacent a compression chamber outlet end of a compression chamber of the screw compressor, and an actuator structure coupled to the linear valve member and orienting the linear valve member to move radially along the compression chamber outlet end of the compression chamber, thereby adjusting the radial position at which gas exits the compression chamber, the actuator structure coupled to a shutter of a spiral valve of the screw compressor to move the linear valve based on a position of the spiral valve of the screw compressor.

Description

[Technical Field]

[0001] The present disclosure relates to screw compressors, and more particularly to screw compressors having a control mechanism that can vary the compressor volume index. [Background technology]

[0002] It is believed that screw gas compressors are known in the prior art. In the prior art, a screw compressor includes a compressor housing and may use a motor (e.g., a permanent magnet rotor / stator motor) to drive one of two compression screws (e.g., a first compression screw). The second compression screw may be mechanically coupled to the compression screw driven by the motor. Thus, the second compression screw may be driven by the first compression screw. In the prior art, gas is drawn into the compressor through an inlet, compressed between the two compression screws as they rotate, and output through a gas inlet and an outlet downstream of the compression screws.

[0003] In some prior art, gas compressors may include a mechanical capacity control mechanism that provides one or more bypass ports or valve openings formed in the compressor housing or rotor cowling to allow gas to exit the housing and control or prevent over-pressurization or over-compression along the length of the compression screw. In the prior art, one or more bypass ports or valve openings may be located adjacent to a spiral valve that controls the opening and closing of the bypass port or valve opening with a shutter that rotates to a point where it disengages from the bypass port and allows one or more of the bypass ports to communicate with a bypass chamber, thereby changing the compression length of the compressor.

[0004] However, in some prior art screw compressors with mechanical capacity control mechanisms, the adiabatic efficiency can be reduced by the amount of power used to recompress gas being fed back from the system to the compressor (undercompression). Furthermore, as the compressor capacity is reduced by the variable capacity mechanism, the specific power (unit: power / volume) increases.

[0005] In the prior art, specific power can be reduced when the compressor Vi (volume index) is corrected to a value appropriate for the effective length determined by the capacity control mechanism. However, prior art variable Vi mechanisms are expensive, significantly increase the compressor envelope, and require complex control systems.

[0006] Furthermore, in the prior art, compressor manufacturers sometimes allow compressors to be used to generate gas pressures other than those for which Vi is optimized, which also reduces adiabatic efficiency. Thus, prior art systems can either increase costs or reduce functionality. Summary of the Invention

[0007] Aspects of the present disclosure may include a compact variable volume indexing valve for a screw compressor, the compact variable volume indexing valve may include a linear valve member disposed adjacent to a compression chamber outlet end of a compression chamber of the screw compressor, and an actuator structure coupled to the linear valve member and orienting the linear valve member to move radially along the compression chamber outlet end of the compression chamber, thereby adjusting the radial position at which gas exits the compression chamber, the actuator structure coupled to a shutter of the spiral valve of the screw compressor to move the linear valve based on the position of the spiral valve of the screw compressor.

[0008] Another aspect of the present disclosure may include a screw compressor having a compressor housing defining a compression chamber having a compression chamber outlet end and a plurality of bypass ports in communication with the compression chamber, a spiral valve disposed adjacent to the plurality of bypass ports in communication with the compression chamber and including a shutter configured to selectively open and close one or more of the plurality of bypass ports based on a rotational position of the spiral valve, and a compact variable volume indexing valve. The compact variable volume indexing valve may include a linear valve member disposed adjacent to the compression chamber outlet end of the compression chamber, and an actuator structure coupled to the linear valve member and configured to move the linear valve member radially along the compression chamber outlet end of the compression chamber, thereby adjusting the radial position at which gas exits the compression chamber, the actuator structure coupled to the shutter of the spiral valve of the screw compressor to move the linear valve based on a position of the spiral valve of the screw compressor.

[0009] In an additional aspect of the present disclosure, the actuator structure may include a toothed region on the linear valve member and a toothed gear that engages the toothed region of the linear valve member, the toothed gear being coupled to a shaft extending from the shutter of the spiral valve.

[0010] In an additional aspect of the present disclosure, the linear valve member may have a semi-cylindrical shape.

[0011] In an additional aspect of the present disclosure, a linear valve member may be inserted into a radial bore formed in the compressor housing.

[0012] In an additional aspect of the present disclosure, a linear valve member may be inserted into the radial bore such that it is offset from a centerline of the radial bore toward the compression chamber outlet end. [Brief explanation of the drawings]

[0013] A general configuration for implementing various features of the present disclosure will now be described with reference to the drawings. The drawings and associated description are provided to illustrate exemplary embodiments of the present disclosure and are not intended to limit the scope of the disclosure. Reference numbers are reused throughout the drawings to indicate correspondence between referenced elements. [Figure 1] FIG. 1 is a perspective view of a screw compressor according to an exemplary embodiment of the present disclosure. [Figure 2] FIG. 2 is a side view of the screw compressor shown in FIG. 1 according to an exemplary embodiment of the present disclosure. [Figure 3] FIG. 2 is an end view of the screw compressor shown in FIG. 1 according to an exemplary embodiment of the present disclosure. [Figure 4] FIG. 2 is a top view of the screw compressor shown in FIG. 1 according to an exemplary embodiment of the present disclosure. [Figure 5] FIG. 4 is a cross-sectional view of the screw compressor taken along line VV′ in FIG. 3. [Figure 6] FIG. 6 is a cross-sectional view of the screw compressor taken along line VI-VI′ in FIG. 3. [Figure 7] FIG. 7 is a cross-sectional view of the screw compressor taken along line VII-VII′ in FIG. 3. [Figure 8] FIG. 8 is a cross-sectional view of the screw compressor taken along line VIII-VIII′ in FIG. 4. [Figure 9] 9 is a cross-sectional view of the screw compressor taken along line IX-IX' in FIG. 2. [Figure 10] 3 is a cross-sectional view of the screw compressor taken along line XX' in FIG. 2. [Figure 11] FIG. 9 is an enlarged view of the small variable Vi valve shown in FIG. 8. [Figure 12] FIG. 11 is an enlarged view of the small variable Vi valve shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] The following detailed description provides further details of the figures and exemplary embodiments of the present disclosure. For clarity, reference numbers and descriptions of elements that are duplicated between figures have been omitted. Terms used throughout this specification are provided by way of example and are not intended to be limiting in any way. For example, the use of the term "automatic" can include fully automatic implementations or semi-automatic implementations with user or operator control over certain aspects of the implementation, depending on the desired implementation of one skilled in the art practicing embodiments of the present disclosure. Furthermore, sequence terms such as "first," "second," "third," etc. may be used in the specification and claims for descriptive purposes only and are not intended to be limited to referring to described acts or items occurring in the described order. Acts or items may be arranged in different orders, or performed in parallel or dynamically, without departing from the scope of the present disclosure.

[0015] As explained above, in some prior art screw compressors with mechanical capacity control mechanisms, the adiabatic efficiency can be reduced by the amount of power required to recompress gas being fed back from the system to the compressor. Furthermore, reducing the compressor capacity with a variable capacity mechanism increases the specific power output. To address this, prior art systems may use a mechanism to adjust the compressor volume index (Vi) based on the effective length of the compressor, as determined by the capacity control mechanism. However, prior art variable Vi control mechanisms are expensive, significantly increase the compressor envelope, and require complex control systems.

[0016] To address these issues, exemplary embodiments of the present disclosure may include a CVVV (Mini Variable Vi Valve) that can reduce the size of the exhaust port (which determines Vi) by raising the lower edge of the exhaust port so that Vi may be optimized for the capacity available at the maximum capacity reduction determined by the mechanical capacity control system. In some exemplary embodiments, the CVVV may include a radial slide valve integrated into the rotor housing exhaust face that, when moved downward, effectively lowers the lower edge of the port, thereby increasing the size of the exhaust port and optimizing Vi for the new higher capacity determined by the mechanical capacity control system.

[0017] As described in this disclosure, the CVVV can be applied to one or both sides of the exhaust port and can be configured for actuation by a rack gear that contacts a pinion on an existing spiral valve mechanism, or by actuation using an electric stepper motor, linear motor, air cylinder, hydraulic cylinder, or similar device. In some exemplary embodiments, using a single valve can be cost-effective, while two valves can improve performance. Because the valve opens and closes radially from the exhaust port, it utilizes space that would normally be unused because that area is normally used as a path for exhaust gases.

[0018] Additionally, the variability of the CVVV may provide a cost-effective way to optimize Vi for gas production at various pressures. In this application, the CVVV will most likely not be actuated by a rack and pinion mechanism, but by one of the other various methods listed above.

[0019] FIG. 1 is a perspective view of a screw compressor 100 having a spiral valve structure according to an exemplary embodiment of the present application. Additionally, FIGS. 2-4 are a side view, an end view, and a top view, respectively, of the screw compressor 100 according to an exemplary embodiment of the present application. As shown, the screw compressor 100 includes a compressor housing 10 that encloses the compressor internals and defines a compression chamber 3 (not shown in FIGS. 1-4, but shown in FIGS. 5-8). The housing 10 may include one or more mounting brackets or feet 2 that support the screw compressor 100 and allow it to be secured to a support platform such as a floor. For example, the feet 2 may allow the screw compressor 100 to be mounted to a portable support platform or trailer.

[0020] The housing 10 also defines a main gas flow inlet 26 and a main gas flow exhaust outlet 28. Arrows are intended to illustrate the gas flow through the screw compressor 100. The compressor housing 10 may also allow passage of a drive shaft 15 from the compressor internals (shown in FIGS. 5-8) to the area surrounding the compressor 100.

[0021] The drive shaft 15 may be used to drive the screw compressor 100 by a motor or mechanical coupling to an engine. The screw compressor 100 may be driven by an IC engine such as a gasoline engine, a diesel engine, or any other type of engine that would be apparent to one skilled in the art. The screw compressor 100 may also be driven by an electric motor or any other type of machine that provides rotational power that would be apparent to one skilled in the art.

[0022] Additionally, an actuator module 5 may be mounted to the compressor housing 10 to control a spiral valve structure (shown in FIGS. 5-8) located within the compressor housing 10. As described below, the actuator module 5 may include an electric motor coupled to a gearbox that is coupled to the spiral valve. The actuator module 5 may also include an integrated processor component that may include on-board control logic to control the actuator module 5 automatically, semi-automatically based in part on user input, or manually based entirely on user input. The actuator module 5 may also be used to control a miniature variable viscosity valve (CVVV), as shown in FIGS. 6-10.

[0023] Figures 5 to 8 are cross-sectional views of the screw compressor. Specifically, Figures 5 to 7 are cross-sectional views of the screw compressor taken along lines V-V', VI-VI', and VII-VII' in Figure 3, respectively. Furthermore, Figure 8 is a cross-sectional view of the screw compressor taken along line VIII-VIII' in Figure 4.

[0024] The compressor housing 10 defines a compression chamber 3 that defines two adjacent bores 6 and 8 that contain the screws 7 and 9, respectively, of the twin-screw gas compressor 100 when the unit is assembled and functional. As shown, one screw 7 (also known as the drive screw) is mounted on a driven gear 210 and is mechanically coupled to a shaft 15 by a drive gear 205. The shaft 15 is also coupled to a motor or engine that drives the screw gas compressor. The other screw 7 (also known as the driven screw) is driven by the drive screw 9. Each of the screws 7 and 9 may be supported by a bearing group 225, such as roller bearings, or any other type of bearing or bushing that would be apparent to one skilled in the art.

[0025] Furthermore, in some exemplary embodiments, one of the screws may have a female lobe configuration and the other of the screws may have a male lobe configuration. In other words, one of the screws may be a female compression screw and the other screw may be a male compression screw that mates with the female compression screw. For example, the driving screw 9 may be a male compression screw and the driven screw 7 may be a female compression screw. As will be apparent to one of ordinary skill in the art, exemplary embodiments of the present application are not limited to this configuration, and some exemplary embodiments may have alternative configurations (e.g., the driving screw 9 may be a female compression screw and the driven screw 7 may be a male compression screw).

[0026] The end of the compressor housing 10 includes an outlet 28 in fluid communication with the inlet 26 (shown in FIGS. 1-4). Gas flow channels 215, 220 may connect each of the bores 6, 8 to the inlet 26, thereby permitting gas to flow into each of the bores 6, 8. Each of the bores 6, 8 also includes one or more bypass ports, collectively designated by the numerals 12a-12e. The illustrated bypass ports 12a-12e are formed in the bore 6 associated with the driven screw 7. Additionally, a similar bypass port is formed in the bore 8 associated with the driving screw 9, but is not shown herein. As shown, each bypass port 12a-12e is in fluid communication with a bypass chamber 22 containing a spiral valve 20 rotatable along an axis 24. The length of each of the bores 6, 8 associated with a bypass port 12a-12e may also be referred to as a bypass window 245.

[0027] As described above, the compressor housing 10 has a gas inlet 26 and a gas outlet 28. Within the compressor housing, gas flow channels 215, 220 provide fluid communication between the inlet 26 and the compression chamber 3. As the screws 7 and 9 rotate in their respective bores 6, 8 of the compression chamber 3, gas is compressed inside the compression chamber 3. The compression chamber 3 has a length extending between the compression chamber inlets 230, 235 and the compression chamber outlet end 240. The compressed gas then exits through the gas outlet 28. Arrows indicate the flow of gas through the compression chamber 3.

[0028] 6-8, spiral valve 20 includes shutter 335 that selectively blocks (closes) or opens bypass ports 12a-12e depending on the rotational position of spiral valve 20. When spiral valve 20 is rotated to a point where one or more of bypass ports 12a-12e are in fluid communication with spiral valve chamber 22, the length of compression chamber 3 is reduced, and therefore the effective compression volume of the compression chamber may be reduced.

[0029] 6, bypass ports 12c-12e exhibit flow, while bypass ports 12a and 12b exhibit no flow. With at least one bypass port 12c-12e open, the effective compression length of compression chamber 3 is defined by the distance between the open bypass port closest to compression chamber outlet end 240 and compression chamber outlet end 240 itself.

[0030] This reduction in effective compression volume reduces torque, saves power, increases efficiency, and extends the life of gas compressor components. However, reduced compression capacity can also reduce adiabatic efficiency, as power is used to recompress gas that flows back out of the system.

[0031] The spiral valve 20 is coupled to an actuator module 5 that controls the rotation and position of a shutter 335 of the spiral valve 20. As shown, the actuator module 5 includes a motor 325 that is mechanically coupled to a gearbox 330. The gearbox 330 mechanically couples the motor 325 to the spiral valve 20. Thus, torque from the motor can be transmitted by the gearbox 330 to the shutter 335 of the spiral valve 20, causing the shutter 335 to rotate. The motor 325 can be an electric actuator motor that allows for precise control of the rotational speed and rotational position of the spiral valve.

[0032] The actuator module 5 may be mounted to the compressor housing 10 and adapted to control a spiral valve structure disposed within the compressor housing 10. The actuator module 5 may also include an integrated processor component that may include on-board control logic to control the motor 325 module automatically, semi-automatically based in part on user input, or manually based entirely on user input.

[0033] Spiral valve 20 can be rotated (or actuated) along its axis 24 from a fully open position (where all bypass ports are open) to a fully closed position (where all bypass ports are closed) and all points in between. In Figures 6-8, flow is shown as if spiral valve 20 were rotated to a point that allows partial bypass of gas from compression chamber 3 to bypass chambers 215, 220. Specifically, bypass ports 12c-12e allow gas to flow from compression chamber 3 to bypass chambers 215, 220. Gas flow is represented by arrows.

[0034] The exemplary embodiment of the present disclosure also includes a miniature variable viscosity valve 605 (CVVV), highlighted by an oval in Figures 6-8. The CVVV 605 includes a valve member 620 mechanically coupled to a toothed gear 615 that is coupled to a rotating shaft 610 extending from the shutter 335 of the spiral valve 20. The CVVV 605 is discussed in more detail below.

[0035] Figures 9 and 10 are cross-sectional views of the screw compressor taken along lines IX-IX' and X-X' in Figure 2. The cross-sectional views of Figures 9 and 10 provide end views of the screw compressor showing the main gas outlet 28 and the compression chamber outlet end 240. Figures 9 and 10 also show a compact variable viscosity valve (CVVV) 605. Further, enlarged views of the CVVV 605 are shown in Figures 11 and 12.

[0036] As described above, the CVVV 605 includes a valve member 620 mechanically coupled to a toothed gear 615 that is coupled to a rotating shaft 610 extending from the spiral valve shutter. In some exemplary embodiments, the valve member 620 is a linear member that extends vertically upward into the compression chamber 3 adjacent to the compression chamber outlet end 240. Furthermore, when extended, the valve member 620 may extend radially across the face of the compression chamber outlet end, changing the radial location at which gas exits the compression chamber 3. The valve member 620 may have a cylindrical or semi-cylindrical shape. For example, the valve member 620 may have a semicircular cross section. Furthermore, the valve member 620 may be positioned or inserted into the radial bore 625 formed in the compressor housing 10 such that the valve member 620 is offset from the centerline of the radial bore 625 toward the compression chamber outlet end 240. The offset in the bore 625 may provide a good sealing action relative to the compression chamber outlet end 240.

[0037] For example, the valve member 620 may utilize the inherent sealing properties of a smaller cylinder that can slide inside a slightly larger cylindrical bore that is open to a portion of its circumference on both sides, creating two sealing surfaces on each side of the cylinder. Press-fitting in either direction seals the smaller cylinder against the larger cylindrical bore, sealing the passage and preventing flow around the valve. Furthermore, the centerline of the valve member 620 is offset far enough from the exhaust face so that a sealing surface exists for pressure from either direction. The valve member 620 seal is thus contained below the desired flow path, preventing any flow in that direction. In this way, the valve member 620 may comprise a seal designed to provide radial sealing properties while maintaining an axial seal by allowing the cylinder to move slightly radially.

[0038] The valve member 620 has a flat side so that it can be positioned within the exhaust face without creating voids in the exhaust face that would reduce the compressor's efficiency. Because a portion of the valve member 620 resides within the rotor bore, a valve plug material can be used to fill any voids in the rotor bore surface that could cause gas to leak past the apex of the rotor and into the low-pressure threads. The valve plug material may also be used to maintain the valve orientation so that it does not interfere with rotor movement. The cavity around the actuation side of the valve can be sealed or open to relieve pressure. Open to relieve pressure makes manufacturing and assembly easier.

[0039] In some exemplary embodiments, the valve member 620 may have an actuator structure including a toothed region 630 that engages with a toothed gear 615 and moves linearly upward based on the rotation of the toothed gear 615. The toothed gear 615 is coupled to a shaft 610 extending from the shutter 335 of the spiral valve 20. This configuration may allow the position of the valve member 620 to be controlled by the actuator module 5 that controls the rotation of the shutter 335. Furthermore, the position of the valve member 620 may be adjusted relative to the shutter 335 so that the valve member 620 is optimally positioned for each orientation of the shutter 335 that controls the length of the compression chamber 3.

[0040] The exemplary embodiment of the CVVV 605 is not limited to an actuator structure of a valve member having a toothed region 630 that engages a toothed gear 615 that is coupled to the shutter 335 of the spiral valve 20. In other exemplary embodiments, the CVVV 605 may include an actuator structure featuring a linear actuator, such as a hydraulic cylinder, pneumatic piston, or stepper motor, that is coupled to the shutter 335.

[0041] In some exemplary embodiments, the CVVV 605 can be implemented with one valve member or two valve members. For example, one valve member can be located on the male side of the compression chamber outlet end 240 and one valve member can be located on the female side of the compression chamber outlet end 240. However, if the valve member 620 used is large enough to allow the desired flow, only one valve member per side is required. A single valve configuration is acceptable because the male and female screw lobes 305 / 310 / 315 / 320 interlock and connect to the same compression chamber.

[0042] While the present invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are described in detail herein. It will be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed. Moreover, the exemplary implementations are not limited to industrial or fixed locations. A portable configuration may be achieved by mounting the screw compressor 100 on a portable structure such as a vehicle, trailer, or the like.

[0043] The foregoing detailed description has used diagrams, schematic diagrams, and examples to illustrate various exemplary embodiments of devices and / or processes. To the extent that such diagrams, schematic diagrams, and examples include one or more functions and / or operations, each function and / or operation in such diagrams or examples may be individually and / or collectively realized by a variety of structures. While specific exemplary embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of protection. Indeed, the novel methods and apparatuses described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and changes can be made in the form of the devices and systems described herein without departing from the spirit of protection. The appended claims and their respective equivalents are intended to cover such forms or modifications as fall within the scope and spirit of protection.

Claims

1. 1. A compact variable volume indexing valve for a screw compressor having a compressor housing defining a compression chamber, comprising: a linear valve member disposed adjacent the compression chamber outlet end of the compression chamber; an actuator structure coupled to the linear valve member and oriented to move the linear valve member radially along the compression chamber outlet end of the compression chamber to adjust the radial position at which gas exits the compression chamber; Equipped with A compact variable volume indexing valve, wherein the actuator structure is coupled to a shutter of the spiral valve of the screw compressor to move the linear valve member based on the position of the spiral valve of the screw compressor.

2. The actuator structure comprises: a toothed region on the linear valve member; a toothed gear engaging the toothed region of the linear valve member; Equipped with 2. The compact variable volume indexing valve of claim 1, wherein the toothed gear is coupled to a shaft extending from the shutter of the spiral valve.

3. 10. The compact variable volume indexing valve of claim 1, wherein the linear valve member has a semi-cylindrical shape.

4. 2. The compact variable volume indexing valve of claim 1, wherein the linear valve member is inserted into a radial bore formed in the compressor housing.

5. 5. The compact variable volume indexing valve of claim 4, wherein the linear valve member has a cylinder inserted into the radial bore along an axial direction of the linear valve member and movable inside the radial bore in a radial direction of the linear valve member to form a sealing surface against the inside of the radial bore.

6. a compressor housing defining a compression chamber having a compression chamber outlet end and a plurality of bypass ports in communication with said compression chamber; a spiral valve including a shutter disposed adjacent to the plurality of bypass ports communicating with the compression chamber, the shutter configured to selectively open and close one or more of the plurality of bypass ports based on a rotational position; It is a small variable volume index valve, a linear valve member disposed adjacent the compression chamber outlet end of the compression chamber; an actuator structure coupled to the linear valve member and oriented to move the linear valve member radially along the compression chamber outlet end of the compression chamber to adjust the radial position at which gas exits the compression chamber; A small variable volume index valve equipped with Equipped with the actuator structure is coupled to the shutter of the spiral valve of the screw compressor to move the linear valve member based on a position of the spiral valve of the screw compressor; Screw compressor.

7. The actuator structure comprises: a toothed region on the linear valve member; a toothed gear engaging the toothed region of the linear valve member; Equipped with The screw compressor according to claim 6 , wherein the toothed gear is coupled to a shaft extending from the shutter of the spiral valve.

8. 7. The screw compressor of claim 6, wherein the linear valve member has a semi-cylindrical shape.

9. 7. The screw compressor of claim 6, wherein the linear valve member is inserted into a radial bore formed in the compressor housing.

10. 10. The screw compressor of claim 9, wherein the linear valve member includes a cylinder inserted into the radial bore along an axial direction of the linear valve member and movable inside the radial bore in a radial direction of the linear valve member to form a sealing surface against the inside of the radial bore.

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