Patent Application
20050276712
This invention relates generally to the field of check valves and, more particularly, to an improved inlet check valve for use with a high pressure waterjet intensifier.
A waterjet intensifier has a high pressure cylinder of, for example, up to 40,000 psi or greater; and fluid to the high pressure cylinder is supplied via an inlet check valve that also must be capable of operating reliably at such high pressures. One example of an inlet check valve assembly is described in U.S. Pat. No. 6,021,810, which discloses an inlet valve mounted on the end of a projecting portion of a generally cylindrical check valve body. The inlet check valve has a ball valve element that is mounted over an inlet passage. Such a check valve functions well in service, however, the design does have an opportunity for an improvement. The valve body is made of a steel material that is not as hard as the ball valve. After some time in service, the repetitive action of the ball valve being pushed against the valve body seat by the high pressure liquid results in wear on the valve body where the ball valve seats. After continued use, the inlet check valve should be serviced, which requires that the valve body be machined or replaced to restore a high quality inlet valve seat. Such a servicing process is costly and labor intensive. Consequently, there is the need for an improved inlet check valve that has a longer useful life.
The present invention provides an inlet check valve that provides a long, highly reliable service life. In addition, the inlet check valve of the present invention isolates all wear parts; and while such isolation requires extra static seals, additional sealing components are not required, which would otherwise reduce the service life of the inlet check valve. Further, the inlet check valve of the present invention permits all wear parts to be easily and quickly replaced in the field, thereby substantially reducing the cost of servicing the inlet check valve. Thus, the inlet check valve of the present invention is especially useful in high pressure cylinders that require a long service life.
In accordance with the principles of the present invention and in accordance with the described embodiments, the present invention provides an inlet check valve mounted with first and second fasteners to an end surface of a projection extending from one end of a valve body. The valve body has inlet and outlet passages intersecting the projection end surface, and the valve body is mounted to a high pressure pump for conducting a low pressure liquid via the inlet passage to the high pressure pump and conducting a high pressure liquid via the outlet passage from the high pressure pump. The inlet check valve has an inlet seat with first and second through-holes locatable adjacent the inlet passage and the outlet passage, respectively, and third and fourth through-holes receiving the first and second fasteners, respectively. A first surface on the inlet seat is locatable against the projection end surface and forms a liquid tight seal therewith.
A valve is positionable over the first through-hole to define a closed valve position blocking a flow of liquid past the valve and through the inlet passage. An inlet guide has first and second through-holes alignable with respective first and second through-holes of the inlet seat. Third and fourth through-holes of the inlet guide are locatable adjacent the third and fourth through-holes of the inlet seat, respectively, and also receive the first and second fasteners, respectively. A cavity in the inlet guide is aligned with the first through-hole of the inlet seat and maintains the valve between the cavity and the first through-hole of the inlet seat. The valve is positionable in the cavity away from the closed valve position to define an open valve position permitting the flow of liquid past the valve and through the inlet passage.
In one aspect of the invention, the end surface and the first surface are lapped surfaces. In another aspect of the invention, an alignment component extends into the inlet seat, the end surface and the inlet guide for aligning the inlet guide and the inlet seat with the end surface.
These and other objects and advantages of the present invention will become more readily apparent during the following detailed description together with the drawings herein.
Referring to
Referring to
Above the valve 72 is a cavity 83 of an inlet guide 61. The inlet guide 61 has an upper side or surface 79 with an arcuate or circular periphery extending approximately parallel to the surface 52 of the projection 24. A portion of the upper side 79 forms a flange 80, and an opening or hole 81 is located in the flange 80. The cavity 83 is disposed in an inner or a lower side 87 of the inlet guide flange 80. The cavity 83 has a curved and preferably spherical shape and cross-sectional profile. Thus, the valve 72 is able to move freely in the cavity 83 and in a direction generally parallel to a centerline 63 of the valve body 22. The displacement or lift of the valve 72 is fixed by the height of the cavity 83 above the end surface 52 and the size of the valve 72, for example, the diameter of the valve 72. The hole 81 is radially displaced from the centerline 63 of the valve body 22 and is concentric with the fluid inlet path 55 in the inlet seat 59, which, in turn, is concentric with, and intersects, the valve body fluid inlet passage 50.
Referring to
Referring to
The inlet guide 61 further includes an off-center, high pressure fluid outlet path 93 that is concentrically alignable with a fluid outlet bore 94 in the inlet seat 59, which, in turn, is concentrically alignable with an outlet fluid passage 96 within the valve body 22. The outlet fluid passage 96 provides a fluid exit from the valve body 22 in a known manner via an outlet check valve (not shown).
The valve body projection surface 52 and its opposing surface 106 on the inlet seat 59 are made with a lapped finish. Therefore, lapped surfaces 52, 106, when brought together, form a liquid-tight static seal around the fluid outlet bore 94 and the outlet fluid passage 96. Thus, even though the addition of the inlet seat 59 increases the number of static seals required, such static seal is provided by the contacting lapped surfaces 52, 106 without the use of separate sealing components, for example, O-rings.
In use, referring to
The operation of the valve described herein provides superior performance. It is believed that the curved shape of the outer surface of the valve 72 provides less resistance in the closing process; and therefore, the valve 72 is more responsive and closes faster than other valves. Normally, the piston 101 is powered by a reciprocating pump which creates significant pressure spikes in reversing direction. An accumulator is used to absorb the changes in pressure, but the hydraulic system still experiences pressure spikes. The faster response of the valve 72 minimizes those pressure spikes and provides a generally improved and smoother operation.
The inlet seat 59 is made from a hard stainless steel, for example, a 0.812Å 15-5 PH H900 stainless steel, which is harder than the material used to make the valve body 22. The inlet guide 61 is also made from a stainless steel, for example, a 300 series stainless steel. With such materials, the inlet 53 provides a valve seat that has a substantially longer service life than valve seats located in the end surface 52 of the projection 24 as is done in comparable known valves.
However, when it is desired to service the inlet check valve 70, the end cap 38 is unscrewed from the end 40 of the cylinder 30; and the valve body 22 is removed from the end of the cylinder 30. Removing the screws 88, 89 releases the inlet guide 61, valve 72 and inlet seat 59 from the valve body projection 24. A new inlet valve seat 59 is installed by inserting the locating pin 86 extending from the surface 106 into the locating hole 67 of the valve body projection 24. A new valve 72 is placed on the inlet 53, and the locating hole 84 in the inlet guide 61 is placed over the locating pin 86 extending from the surface 104 of the inlet seat 59. The screws 88, 89 are inserted through respective clearance holes 69, 71, 73, 75 and into respective threaded holes 91, 92. The curved or spherical shape of the outer surface of the valve 72 automatically aligns the valve 72 in its desired concentric position with respect to the inlet 53, and the screws 88, 89 are tightened to complete assembly of the check valve 70. Further, if the screws 88, 89 are not fully tightened or loosen during operation, the valve 72 cannot move but maintains its desired concentric relationship with the inlet 53.
The inlet check valve 70 described herein has several advantages. First, the use of the harder inlet seat 59 provides the inlet check valve 70 with a substantially longer service life than comparable known valves. Second, the additional static seals required by the inlet seat 59 are achieved without requiring separate sealing components such as O-rings, which also contributes to the increased service life of the inlet check valve 70. Third, the valve 72 and inlet seat 59 are not permanently connected to any other components and therefore, can be individually replaced, thereby substantially reducing the cost of servicing the inlet check valve 70. Thus, the inlet check valve 70 provides a long, highly reliable operation, can be easily and quickly serviced in the field and is especially adaptable for use in high pressure cylinders.
While the invention has been set forth by a description of the preferred embodiment in considerable detail, it is not intended to restrict or in any way limit the claims to such detail. Additional advantages and modifications will readily appear to those who are skilled in the art. For example, while the cavity 83 is shown as being a mating partial spherical shape, the cavity may be conical or any other shape that is effective to receive and maintain a valve in its desired operating position with respect to the inlet 53. Further, in the disclosed embodiment, the valve 72 is spherical; however, as will be appreciated, the valve can be any shape that can be held captured by the cavity 83 and provides a circular line of contact with the inlet 53 when the valve is in the closed position. For example, the valve could be conical in shape, have a bull nose shape or be curved but not spherical. As will be appreciated, in an alternative embodiment, the valve 72 can be a poppet that covers the inlet fluid path 55. In addition, the orifice illustrated as being the opening 81 is shown as a single cylindrical hole; however, an opening or openings of any size, shape and number may be used to facilitate the application of a closing pressure force onto the valve 72.
As will be appreciated, the locations of one or both of the locating holes 84, 67 and the locating pin 86 may be reversed such that the locating hole extends through the inlet valve seat 59 and locating pins are attached to the inlet guide 61 and projection 24, respectively. Further, in the disclosed embodiment, the major cross-sectional profile of the inlet guide 61, that is, the cross-sectional profile taken right below the upper surface 79, is generally arcuate and specifically circular. However, the inlet guide 61 may have a noncircular shape such that the major cross-sectional profile is octagonal, hexagonal or an irregular shape. Further, it is not required that the inlet guide 61 and inlet seat 59 cover the outlet fluid passage 96. For example, an inlet guide 61 may be made that eliminates the portion of the mounting plate shown to the left of the phantom line 107 in
Therefore, the invention in its broadest aspects is not limited to the specific detail shown and described. Consequently, departures may be made from the details described herein without departing from the spirit and scope of the claims which follow.
