Patent Application
20070065320
1. Field of the Invention
This invention relates to the field of pumps and more particularly to a pump with an enhanced high-pressure seal.
2. Description of the Related Art
High pressure pumps are used in many applications including hydraulic systems, pressure washers and presses. A high-pressure pump is described in U.S. Pat. No. 6,092,370 to Tremoulet, Jr. et al., issued on Jul. 25, 2000 and is hereby incorporated by reference in its entirety.
Often, high pressure pumps are used in applications where leaks are a problem. For example, a leaking pump in an airplane may cause the loss of hydraulic fluid. Furthermore, the lost fluid may create an environmental issue or, at least, may create a stain or a slippery area that may contribute to falling or slipping danger.
One problem area in high pressure pumps is the high pressure seal which helps keep pressurize fluids inside the pump. At high pressures, some exceeding 100,000 psi, high pressure seals often fail. It is believed that leaking of the high pressure seal may be the most common problems in high pressure pumps. The failure usually begins with a slow leak, wherein the pump is fully functional and only a small amount of fluid is lost. Furthermore, beyond a slight loss in output pressure, leaks from the high pressure seal can also impact other parts of the pump through loss of lubrication, fatigue and corrosion.
This problem is known in the industry and has been addressed by many solutions including placing a higher, more even force on the seal. For example, US Publication 2005/0074350A1 to Raghavan, et al., published Apr. 7, 2005, describes a “Device and Method for Maintaining a Static Seal of a High Pressure Pump,” and is hereby incorporated by reference. A pump is described in U.S. Pat. No. 3,966,360 to Greene, issued Jun. 29, 1976. This pump has an outer casing forming a reservoir. Such solutions may improve the performance of such seals, but they do not prevent the problem and, when a seal leaks, the loss of fluid or the resulting spill may cause problems.
What is needed is a pump with a high pressure seal in which any leaking in the high pressure seal feed back into the input chamber of the pump.
In one embodiment, a pump is disclosed including a cylinder in which a fluid is compressed, an inlet for accepting a fluid into the pump, an inlet area connected to the inlet for transporting the fluid across the pump and a feed tube for transporting the fluid from the inlet area to the cylinder. A check valve is provided to allow the fluid to flow from the feed tube and into the cylinder while blocking the flow of the fluid from the cylinder back into the feed tube. A piston is configured within the cylinder for compressing the fluid and a piston rod is coupled to the piston for exerting force on the piston. The piston is held within the cylinder by a high pressure seal. A high-pressure output port is connected to the cylinder for outputting the fluid under pressure. The high pressure seal interfaces with the inlet area so that any leakage of the fluid through the high pressure seal leaks back into the inlet area.
In another embodiment, a method of reducing leakage in a pump is disclosed including providing a fluid into an inlet of a pump, the fluid flowing through an inlet area and flowing through a feed tube and flowing through a check valve and into a cylinder; then applying force to the piston within the cylinder to pressurize the fluid. The check valve prevents the fluid from leaving the cylinder back into the feed tube. The piston and cylinder are sealed using a high pressure seal and potential leakage is captured from the high pressure seal by interfacing the high pressure seal with the inlet area.
In another embodiment, a pump is disclosed including a cylinder having a bore in which a fluid may be compressed with an inlet for accepting the fluid into the pump and an inlet area connected to the inlet for conducting fluid across the pump. A feed tube for transports the fluid from the inlet area to a first end of the cylinder and a check valve allows the fluid to flow in one direction into the first end of the cylinder from the feed tube. A piston within the cylinder compresses the fluid whereby a piston rod coupled to the piston exerts force on the piston. A high pressure seal is provided for retaining the piston within the cylinder while retarding the fluid from leaking from the cylinder under pressure and a high-pressure output port is connected to a second end of the cylinder for outputting the fluid under pressure. The high pressure seal interfaces with the inlet area such that any leakage of the fluid through the high pressure seal feeds back into the inlet area.
The invention can be best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings in which:
Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Throughout the following detailed description, the same reference numerals refer to the same elements in all figures.
Referring to
Referring now to
In some embodiments, a second check valve 18 is adapted within the piston 26, restricting the direction of flow of fluid, allowing flow from within the cylinder 27 below the piston 26 into the cylinder 27 above the piston 26. A high pressure seal 14 helps prevent fluid under a high pressure from leaking while a low-pressure seal 12 helps prevent low pressure fluid from leaking. A guide bushing 9 keeps the low pressure seal 12 in place. To prevent external leakage of fluid, the high pressure seal 14 is interfaced and enclosed by the fluid inlet area 13 such that leakage through the high pressure seal 14 will seep into the fluid inlet area 13 and re-circulate through the pump 10 instead of exiting the pump 10.
Referring now to
Being that the fluid is under a very high pressure, a high pressure seal 14 helps prevent the high pressure liquid from leaking out of the pump. A low pressure seal 12 is provided to help keep low pressure fluids from leaking out of the pump 10. A guide bushing 9 keeps the low pressure seal 12 in place. Being that the high pressure seal interfaces with the fluid inlet area 13, any fluid leaking through the high pressure seal 14 will re-circulate through the inlet area 13 and mix with low pressure fluid, flowing back through the feed tube 24 into the pump 10 instead of exiting the pump.
Equivalent elements can be substituted for the ones set forth above such that they perform in substantially the same manner in substantially the same way for achieving substantially the same result. Although the above description describes a double acting pump, in that a symmetrical pressure is created on both the up stroke and the down stroke, the same high-pressure seal and fluid inlet area interface can be equally applied to a single action pump without veering from the present invention.
It is believed that the system and method of the present invention and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely exemplary and explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.
