HIGH-PRESSURE CYLINDER ASSEMBLY FOR WATERJET INTENSIFIER PUMPS, AND RELATED METHODS
A high-pressure cylinder assembly for use with a waterjet intensifier pump includes a cylinder having a through bore and a radially inner surface extending along a length of the cylinder. A ceramic liner is provided in the through bore and contacts the radially inner surface of the cylinder. A first high-pressure seal is provided in the through bore of the cylinder and is constrained at a first end of the through bore. A second high-pressure seal is provided in the through bore and is constrained at a second end of the through bore. The first and second high-pressure seals are configured to maintain a sealed environment within the high-pressure cylinder assembly during operation of the waterjet intensifier pump.
The present invention relates generally to waterjet intensifier pumps, and more particularly to high-pressure cylinder assemblies for use with waterjet intensifier pumps.
BACKGROUNDWaterjet systems emit highly pressurized streams of water, for example at pressures ranging from 40,000 psi to 100,000 psi, or more. These systems are widely used in various industries for cutting materials such as metal, glass, stone, tile, and food products. Traditional waterjet systems often include an intensifier pump for pressurizing the water and high pressure tubing to deliver pressurized water to a cutting head, which then directs the pressurized water toward a target object to be cut.
Known intensifier pumps include a centrally positioned hydraulic cylinder assembly, and a pair of high-pressure cylinder assemblies positioned at opposed ends of the hydraulic cylinder assembly. The hydraulic cylinder assembly houses a piston and a pair of elongate plungers extending outwardly from the opposed faces of the piston, and into the high-pressure cylinder assemblies. As the piston reciprocates within the hydraulic cylinder under forces exerted by pressurized hydraulic fluid, the plungers are driven back and forth in a rapid alternating manner through inner bores formed in the high-pressure cylinder assemblies. Low-pressure water fed into each of the high-pressure cylinders is pressurized by the corresponding plunger, and the pressurized water is then forced out of its respective high-pressure cylinder through an outlet, such as an outlet port of a corresponding check valve assembly.
During normal operation of a traditional intensifier pump, components of the high-pressure cylinder assembly are exposed to rapid pressure fluctuations ranging 0 to 55,000 psi occurring approximately 20-30 times per minute, with pressure spikes of 100,000 psi or more, pressure cavitations, and water contaminants. Accordingly, it is critical that the components of the high-pressure cylinder assembly are formed with materials capable of withstanding these harsh operating conditions in order to ensure a long operative life.
Known high-pressure cylinders are formed of stainless steel, and include a through bore and a stainless steel radially inner surface that is honed and polished to a smooth finish for minimizing imperfections in the surface. However, even after being finely machined, this stainless steel inner surface unavoidably still includes minor imperfections. When subjected to the extreme pressures within the high-pressure cylinder during operation of the intensifier pump, these imperfections become points of vulnerability at which stresses may concentrate and form small cracks in the cylinder wall. With continued use of the intensifier pump, these cracks may propagate radially outward and lead to complete structural failure of the high-pressure cylinder.
The imperfections in the stainless steel inner surface of the high-pressure cylinder, when subjected to the high-pressure environment, may also initiate axially extending leak paths in the cylinder wall. Such leak paths are destructive to not only the high-pressure cylinder, but also to high-pressure seals disposed at proximal and distal ends of the cylinder through bore. These high-pressure seals ensure that the pressurized water does not leak at the proximal and distal ends, and that the pressurized water is directed fully through an outlet at the distal end. Failure, or even slight degradation, of these high-pressure seals can result in significant performance losses of the intensifier pump. Therefore, maintaining structural integrity of the high-pressure seals is also highly desirable.
Further, not only are the imperfections in the stainless steel inner surface vulnerable to the extremely high pressures experienced during operation of the intensifier pump, they are also particularly vulnerable to corrosion induced by stray contaminants in the water. Corrosion generally increases the size and severity of the imperfections, which may in turn lead to formation of cracks, the propagation of which may lead to complete structural failure of the high-pressure cylinder, as described above.
Accordingly, there remains a need for an improved high-pressure cylinder assembly for use in waterjet intensifier pumps, in which the radially inner surface that contacts the water is more resilient and less susceptible to imperfections and corrosion than that of known stainless steel cylinders, so as to improve operative longevity of the high-pressure cylinder and the high-pressure seals.
SUMMARYIn accordance with an embodiment of the invention, a high-pressure cylinder assembly is provided for use with a waterjet intensifier pump for pressurizing water. The high-pressure cylinder assembly includes a cylinder having a through bore and a radially inner surface extending along a length of the cylinder. The high-pressure cylinder assembly further includes a ceramic liner provided in the through bore of the cylinder and contacting the radially inner surface of the cylinder. A first high-pressure seal is provided in the through bore of the cylinder and is constrained at a first end of the through bore. A second high-pressure seal is provided in the through bore of the cylinder and is constrained at a second end of the through bore. The first and second high-pressure seals are configured to maintain a sealed environment within the high-pressure cylinder assembly during operation of the waterjet intensifier pump.
In accordance with another embodiment of the invention, a waterjet intensifier pump includes a hydraulic cylinder assembly and first and second high-pressure cylinder assemblies coupled to the hydraulic cylinder assembly. The first high-pressure cylinder assembly includes a cylinder having a through bore and a radially inner surface extending along a length of the cylinder. A ceramic liner is provided in the through bore of the cylinder and contacts the radially inner surface of the cylinder. A first high-pressure seal is provided in the through bore of the cylinder and is constrained at a first end of the through bore. A second high-pressure seal is provided in the through bore of the cylinder and is constrained at a second end of the through bore. The first and second high-pressure seals are configured to maintain a sealed environment within the first high-pressure cylinder assembly during operation of the waterjet intensifier pump.
In accordance with yet another embodiment of the invention, a method is provided for pressurizing water with a waterjet intensifier pump including a hydraulic cylinder assembly and a high-pressure cylinder assembly coupled to the hydraulic cylinder assembly. The high-pressure cylinder assembly includes a cylinder having a through bore and a radially inner surface. The high-pressure cylinder assembly further includes a ceramic liner provided in the through bore and contacting the radially inner surface, a pressurization chamber defined by the ceramic liner, and a high-pressure seal provided at an end of the through bore. The method includes receiving water into the pressurization chamber through an inlet. A plunger is driven through the high-pressure seal and into the pressurization chamber to pressurize the water, the water being allowed to contact the ceramic liner during pressurization. Pressurized water is then forced out of the high-pressure cylinder assembly through an outlet.
Various additional features and advantages of the invention will become more apparent to those of ordinary skill in the art upon review of the following detailed description of the illustrative embodiments taken in conjunction with the accompanying drawings.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.
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The hydraulic cylinder assembly 12 includes a hydraulic cylinder 18 closed at its first end by a first hydraulic cylinder end closure 20 and at its opposed second end by a second hydraulic cylinder end closure 22. A plurality of tie rods 24, for example four tie rods 24, are spaced circumferentially about the hydraulic cylinder 18 and extend through each of the first and second end closures 20, 22. Each end of each tie rod 24 may be fitted with at least one nut 26 for holding the end closures 20, 22 and the hydraulic cylinder 18 in secure axial compression, and thereby maintaining the hydraulic cylinder assembly 12 in assembled form. The hydraulic cylinder 18 houses a piston-plunger assembly 28 including a central piston 30 and first and second elongate plungers 32 and 34, respectively, coupled to and extending outwardly from opposed axial faces of the piston 30. The piston 30 includes an annular piston seal 36 that sealingly engages a radially inner surface 38 of the hydraulic cylinder 18. In one embodiment, the piston 30 may be formed of a stainless steel, and the plungers 32, 34 may be formed of a high grade ceramic material such as yttria tetragonal zirconia polycrystal (“YTZP”), formed through hot isostatic pressing (“HIP”), for example.
The hydraulic cylinder 18 defines a hydraulic chamber 40 that houses a hydraulic fluid. Each hydraulic cylinder end closure 20, 22 includes a respective hydraulic fluid port 42, 44 that communicates with the hydraulic fluid chamber 40 and is adapted to transfer hydraulic fluid between the hydraulic chamber 40 and a conduit coupled to a hydraulic pump, as shown schematically in
The first and second hydraulic cylinder end closures 20, 22 further include respective first and second sensor ports 43 and 45, each configured to receive a respective proximity sensor (not shown) for sensing a position of the piston-plunger assembly 28 during its reciprocation. In
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The high-pressure cylinder assembly 14 further includes a ceramic liner 70 having a tubular liner wall 72 and a liner through bore 74 defining a radially inner surface 76. As shown best in
In the embodiment shown, the ceramic liner 70 is formed with an outer diameter that is slightly greater than an inner diameter of the cylinder through bore 54, so as to provide an interference fit with the high-pressure cylinder 46. One method of inserting the ceramic liner 70 into the cylinder through bore 54 during assembly may include heating the high-pressure cylinder 46 so that that it expands radially, and/or cooling the ceramic liner 70 so that it contracts radially. Another method of inserting the ceramic liner 70 into the cylinder through bore 54 may include mechanically stretching the high-pressure cylinder 46 radially outward. Advantageously, following insertion of the ceramic liner 70 into the cylinder through bore 54, the high-pressure cylinder 46 exerts a constant, radially inwardly directed force on the ceramic liner 70 so as to prestress the ceramic liner 70 and maintain the ceramic liner 70 in radial compression during operation of the intensifier pump 10.
The ceramic liner 70 may be formed of any suitable material that is sufficiently hard and corrosion resistant to withstand operating conditions inside the high-pressure cylinder assembly 14. Such operating conditions may include exposure to water contaminants and internal pressures of up to 100,000 psi or more, as described above. In one embodiment, the ceramic liner 70 may be comprised of a high grade ceramic such as yttria tetragonal zirconia polycrystal, formed through hot isostatic pressing, for example. In other embodiments, the ceramic liner 70 may be formed of various alternative suitable materials, including materials having properties similar to those of yttria tetragonal zirconia polycrystal.
The radially inner surface 76 of the ceramic liner 70 is preferably formed with a surface roughness that is smoother than that traditionally achievable for a radially inner surface of a high-pressure cylinder formed of a stainless steel using known finishing methods. In one embodiment, the radially inner surface 76 of the ceramic liner 70 may be formed with a surface roughness of approximately 2 root meat square (“RMS”) or less, which may be achieved through grinding and polishing. For example, the radially inner surface 76 may be formed with a surface roughness of approximately 1-2 RMS. Additionally, as shown, the cylinder wall 52 may be formed with a radial thickness that is greater than a radial thickness of the liner wall 72. In one embodiment, the ceramic liner 70 may be formed with an outside diameter of approximately 1.625 inches and an inside diameter of approximately 1.125 inches, thereby yielding a radial thickness of liner wall 72 of approximately 0.250 inches.
The high-pressure cylinder assembly 14 further includes a cylinder spacer 80 that is received within the ceramic liner through bore 74, after insertion of the ceramic liner 70 into the cylinder through bore 54, as best shown in
As shown in
The cylinder spacer 80 may be formed with a length that is less than that of the ceramic liner 70 and the high-pressure cylinder 46. As such, the cylinder spacer 80 may operate to properly position high-pressure seals 100, 102 along the central axis of the high-pressure cylinder assembly 14. In particular, after the cylinder spacer 80 is received within the ceramic liner through bore 74 and is centered along the length of the ceramic liner 70 and the high-pressure cylinder 46, a proximal seal pocket 104 and a distal seal pocket 106 are formed by the radially inner surface 76 of the ceramic liner 70 and the ends proximal and distal ends of the cylinder spacer 80. The proximal seal pocket 104 is formed between the proximal hub 82 of the cylinder spacer 80 and the proximal end 48 of the high-pressure cylinder 46, and the distal seal pocket 106 is formed between the distal hub 84 of the cylinder spacer 80 and the distal end 50 of the high-pressure cylinder 46.
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During this exhaust stroke within the second high-pressure cylinder assembly 16, the second plunger 34 compresses and thereby pressurizes the water contained within its pressurization chamber 94. The highly-pressurized water is forced out through the opened outlet check valve 130 in a direction toward the attenuator 156. While being discharged, the high-pressure water simultaneously exerts a force against the inlet check valve 128 of the second cylinder assembly 16 and thereby secures it in a closed position.
As the high-pressure water advances toward the attenuator 156, a portion may be bled off and routed toward the first high-pressure cylinder assembly 14 to secure its outlet check valve 130 in a closed position while the first plunger 32 performs an intake stroke within the first high-pressure cylinder assembly 14. Simultaneously, in the first cylinder assembly 14, the inlet check valve 128 is opened to allow low-pressure water to flow into the respective pressurization chamber 94.
Referring to
During operation of the intensifier pump 10, water within the pressurization chamber 94 of the high-pressure cylinder assemblies 14, 16 is contained radially by the ceramic liner 70 and is thus blocked from contacting the radially inner surface 56 of the high-pressure cylinder 46. In particular, the water is permitted to flow between the annular cavity 90 and the spacer through bore 88, via radial bores 92, so as to directly contact the radially inner surface 76 of the ceramic liner 70. Accordingly, and advantageously, the radially inner surface 56 of the high-pressure cylinder 46 is protected from accelerated wear otherwise caused by direct exposure to water during pressurization. The working life of the high-pressure cylinder 46 is thus extended by inclusion of the ceramic liner 70.
Furthermore, the radially inner surface 76 of the ceramic liner 70, against which the high-pressure seals 100, 102 are seated, is more resistant to corrosion and development of leak paths than the radially inner surface 56 of the stainless steel high-pressure cylinder 46. Accordingly, inclusion of the ceramic liner 70 advantageously results in extension of the working life of the high-pressure seals 100, 102 as well. As such, inclusion of the ceramic liner 70 aids in maintaining optimal performance characteristics of the intensifier pump 10 and thus the waterjet system in which the intensifier pump 10 operates.
While the present invention has been illustrated by the description of a specific embodiment thereof, and while the embodiment has been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features discussed herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the general inventive concept.
Claims
1. A high-pressure cylinder assembly for use with a waterjet intensifier pump, the high-pressure cylinder assembly comprising:
- a cylinder including a through bore and a radially inner surface extending along a length of the cylinder;
- a ceramic liner provided in the through bore of the cylinder and contacting the radially inner surface of the cylinder;
- a first high-pressure seal provided in the through bore of the cylinder and constrained at a first end of the through bore; and
- a second high-pressure seal provided in the through bore of the cylinder and constrained at a second end of the through bore, wherein the first and second high-pressure seals are configured to maintain a sealed environment within the high-pressure cylinder assembly during operation of the waterjet intensifier pump.
2. The high-pressure cylinder assembly of claim 1, wherein the first and second high-pressure seals are positioned radially inward of and sealingly contact the ceramic liner.
3. The high-pressure cylinder assembly of claim 1, further comprising:
- a spacer positioned radially inward of the ceramic liner and between the first and second high-pressure seals, the spacer including a through bore configured to receive a plunger of the waterjet intensifier pump.
4. The high-pressure cylinder assembly of claim 3, wherein the spacer and the ceramic liner define an annular cavity therebetween, the spacer configured to allow water to flow through the annular cavity during operation of the waterjet intensifier pump.
5. The high-pressure cylinder assembly of claim 1, wherein the ceramic liner extends along a full length of the through bore of the cylinder.
6. The high-pressure cylinder assembly of claim 1, wherein the ceramic liner is formed of yttria tetragonal zirconia polycrystal.
7. The high-pressure cylinder assembly of claim 1, wherein a radially inner surface of the ceramic liner is formed with a surface roughness that is less than or equal to approximately 2 RMS.
8. The high-pressure cylinder assembly of claim 1, wherein an end of the cylinder includes a thread configured to couple the high-pressure cylinder assembly to a hydraulic cylinder of the waterjet intensifier pump.
9. A waterjet intensifier pump comprising:
- a hydraulic cylinder assembly; and
- a first high-pressure cylinder assembly and a second high-pressure cylinder assembly each coupled to the hydraulic cylinder assembly, wherein the first high-pressure cylinder assembly comprises: a cylinder including a through bore and a radially inner surface extending along a length of the cylinder; a ceramic liner provided in the through bore of the cylinder and contacting the radially inner surface of the cylinder; a first high-pressure seal provided in the through bore of the cylinder and constrained at a first end of the through bore; and a second high-pressure seal provided in the through bore of the cylinder and constrained at a second end of the through bore, wherein the first and second high-pressure seals are configured to maintain a sealed environment within the first high-pressure cylinder assembly during operation of the waterjet intensifier pump.
10. The waterjet intensifier pump of claim 9, wherein the first and second high-pressure seals are positioned radially inward of and sealingly contact the ceramic liner.
11. The waterjet intensifier pump of claim 9, wherein the first high-pressure cylinder assembly further comprises:
- a spacer positioned radially inward of the ceramic liner and between the first and second high-pressure seals, the spacer including a through bore configured to receive a plunger of the waterjet intensifier pump.
12. The waterjet intensifier pump of claim 11, wherein the spacer and the ceramic liner define an annular cavity therebetween, the spacer configured to allow water to flow through the annular cavity during operation of the waterjet intensifier pump.
13. The waterjet intensifier pump of claim 9, wherein the ceramic liner extends along a full length of the through bore of the cylinder.
14. The waterjet intensifier pump of claim 9, wherein the ceramic liner is formed of yttria tetragonal zirconia polycrystal.
15. The waterjet intensifier pump of claim 9, wherein a radially inner surface of the ceramic liner is formed with a surface roughness that is less than or equal to approximately 2 RMS.
16. The waterjet intensifier pump of claim 9, wherein an end of the cylinder includes a first thread and the hydraulic cylinder assembly includes a second thread configured to engage the first thread for coupling the first high-pressure cylinder assembly to the hydraulic cylinder assembly.
17. A method of pressurizing water with a waterjet intensifier pump including a hydraulic cylinder assembly and a high-pressure cylinder assembly coupled to the hydraulic cylinder assembly, the high-pressure cylinder assembly including a cylinder having a through bore and a radially inner surface, a ceramic liner provided in the through bore and contacting the radially inner surface, a pressurization chamber defined by the ceramic liner, and a high-pressure seal provided at an end of the through bore, the method comprising:
- receiving water into the pressurization chamber through an inlet;
- driving a plunger through the high-pressure seal and into the pressurization chamber to pressurize the water;
- allowing the water to contact the ceramic liner during pressurization; and
- forcing pressurized water out of the high-pressure cylinder assembly through an outlet.
18. The method of claim 17, wherein allowing the water to contact the ceramic liner includes blocking the water from contacting the radially inner surface of the cylinder.
19. The method of claim 17, wherein the high-pressure cylinder assembly further includes a spacer positioned radially inward of the ceramic liner and within the pressurization chamber, and wherein driving a plunger into the pressurization chamber includes driving the plunger through a through bore of the spacer.
20. The method of claim 19, wherein the spacer and the ceramic liner define an annular cavity therebetween, and wherein allowing the water to contact the ceramic liner includes allowing the water to flow through the annular cavity.
Type: Application
Filed: Apr 7, 2015
Publication Date: Oct 13, 2016
Inventor: Michael E. Gaillard (Joplin, MO)
Application Number: 14/680,603