High pressure pump

Details High pressure pump High pressure pump

1999-04-19

2001-06-05

Thorpe, Timothy S. (Department: 3746)

Pumps

Expansible chamber type

Having pumping chamber pressure responsive distributor

C417S359000, C417S454000, C417S251000, C417S572000, C092S128000

Reexamination Certificate

active

06241492

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to high pressure pumps and, more particularly, relates to an improved high pressure pump of the type commonly used for supplying pressurized fluid to a blasting gun for cleaning or cutting operations.
BACKGROUND OF THE INVENTION
Those familiar with high pressure blasting equipment commonly used in the surface cleaning and material cutting businesses have long desired a cost effective high pressure pump for providing higher pressure to the blasting gun. In most high pressure blasting applications, the fluid pump must be portable since the surfaces to be cleaned or the material to be cut cannot practically be transported to a stationary pump site. In the cleaning industry, blasting gun operators have long recognized the enhanced effectiveness of water blasting at a fluid pressure of 15,000 PSI compared to water blasting at 10,000 PSI. These individuals have also recognized that a system capable of reliably delivering fluid pressures in excess of 30,000 PSI would be markedly more effective for cleaning purposes, and in many instances would replace sand blasting operations. Those involved in using high fluid pressure for cutting operations similarly recognize that high pressure equipment for cutting, for example, reinforced concrete, would be much more efficient if the fluid system which delivered water to the cutting gun could reliably operate at 35,000 PSI compared to 15,000 PSI.
High pressure pumps employing a plurality of plungers and an in-line valve design as disclosed in U.S. Pat. No. 4,551,077 has been successfully used for generating pressures in excess of 15,000 PSI. U.S. Pat. No. 5,302,087 discloses a technique for loading the pump compression rods which reliably seal the suction manifold with both the upstream plunger housing and the downstream discharge housing, thereby reducing leakage and facilitating pump maintenance and repair.
Those skilled in the design and engineering of high pressure pumps have long recognized that significant problems must be overcome to provide a cost effective high pressure pump capable of outputting 30,000 PSI or more. Numerous problems which are either absent or have little effect in the design, manufacture, and operation of a 15,000 PSI pump become critical to the successful operation of a pump capable of delivering 30,000 PSI or more. At these high pressures, the compressibility of water and its effect on pump efficiency must be considered, and accordingly the size of the fluid chamber containing compressed fluid between the plunger at the end of its pumping stroke and the discharge check valve must be limited. Efforts are accordingly undertaken to reducing this “dead zone” chamber, but in many cases such techniques are contrary to the life of the pump and require increased pump maintenance.
As the pressure output for the fluid pump increases, pump parts become more susceptible to galling and to reduced life due to elevated fluid temperatures. The temperature of compressed water increases approximately 3° F. per thousand PSL and accordingly water supplied to the inlet of the pump at 80° F. reaches a temperature in excess of 180° F. while within the pump, thereby adversely effecting the life of seals and contributing to galling of metal pump components.
Although numerous obstacles are encountered developing a reliable high pressure pump capable of delivery pressures of approximately 35,000 PSI to blasting equipment, businesses using such pumps for cleaning or cutting operations have long desired such a pump. The improved high pressure pump as hereafter disclosed will have significant benefits for those involved in the blasting operations. The portable high pressure pump of the present invention is highly reliable, and is able to deliver fluid pressure in excess of 35,000 PSI to the blasting or cutting gun.
SUMMARY OF THE INVENTION
In a preferred embodiment, the high pressure pump utilizes an in-line pump design, wherein the suction valve seat houses at least a portion of both the inlet check valve and the discharge check valve. The suction valve seat is pressed into sealing engagement with the plunger having by a plurality of compression rods spaced circumferentially about the plunger housing. Both the inlet check valve that passes fluid to the pump chamber and the discharge check valve that prevents high pressure downstream fluid from returning to the pump chamber are movable along an axis substantially coincident with the central axis of the corresponding pump plunger.
In order to e the forces acting on the pump compression rods, the diameter of the seal between the suction valve seat and the plunger housing is reduced and, most importantly, a weep groove is provided between the suction valve seat and the plunger housing so that any fluid which bypasses this seal does not contribute to the build up of forces which must be countered by the compression rods. Any fluid passing by this seal instead escapes to the exterior of the plunger housing, where it serves as a visual indication to the pump operator that service of the pump is required. The annular fluid receiving chamber in the suction valve seat is configured to facilitate pre-stressing of the suction valve seat, and to minimize the diameter of the suction valve seat while transmitting forces between the plunger housing and the discharge housing without deforming the suction valve seat. A seal ring is provided on each side of the annular fluid receiving chamber in the suction valve seat to seal between the suction manifold and the suction valve seat, while no seal is provided between the suction manifold and the plunger housing.
In order to minimize stress concentration locations on the plunger housing, this housing is provided with a uniform diameter bore extending axially from the packing for sealed engagement with the plunger to the suction valve seat. A stop sleeve positioned in this bore engages the suction valve seat, and a spring acting between the stop sleeve and a packing ring compresses the packing to reliably seal with the reciprocating plunger. The packing ring is configured to minimize the volume of the pump chamber when the plunger is at the end of its compression stroke, thereby minimizing dead zones within the pump and enhancing pump efficiency.
A gland nut is connected to the end of the plunger housing axially opposite the suction valve seat, and presses against a bronze bushing which in turn presses against the packing. The bronze bushing has an internal bore finish for acting as a bearing for the reciprocating plunger. To reduce maintenance problems associated with the high temperatures produced by the pump, a tungsten carbide sleeve ring is provided between a portion of the bronze bushing and the stainless steel plunger housing, thereby reducing the likelihood of the bronze bushing becoming seized or welded to the plunger housing. To achieve a relatively compact pump design and cool the pump plunger, a cooling fluid port is provided in both the plunger housing and the bushing at a position spaced axially toward the power end of the pump relative to the bronze bushing. Accordingly, the plunger is cooled by fluid engaging the plunger upstream from the bronze bushing, with the cooling fluid being discharged through one or more cooling fluid discharge ports in the gland nut.
At least some of the compression rods are provided with extension studs which are welded to the ends of the compression rods. During repair of the pump, extension rods may be threaded to the extension studs to serve as supports for the torque plate, the discharge housing and the suction manifold. A check valve housing and a gauge adapting plate may each be mounted on opposing sides of the discharge housing to reduce external plumbing connections. After repair of the pump, the extension rods may be easily removed from the extension studs so that the pump size is only slightly increased.
The pump also includes an alignment connector between the plunger and the pump rod which is connected to the power end of the pump. The alignment connector incl

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