This invention pertains to the art of high pressure fluid systems and more particularly to high pressure port fitting systems that connect various fluid system components.
The invention is particularly applicable to a port fitting system that interconnects pressurized tubes, pipes or conduits with related fluid system components such as valves, pumps, or the like. However, it will be appreciated that the invention has broader applications and may be advantageously employed in still other fluid environments and applications.
Pressurized fluid systems all have the primary objective of conveying pressurized fluid from one point to another without developing any leak paths. Two well known structural arrangements are used to interconnect various components of a fluid system without resulting in any significant leakage problems.
According to the first arrangement, pipe threads that interconnect a fluid line with another component maintain a close enough tolerance to seal or close off any potential leak paths. Unfortunately, using the pipe threads as the seal element encounters difficulties under various conditions. For example at higher pressures, leakage may occur along the threads and oftentimes requires the addition of special sealing compounds such as the well known use of Teflon tape. Reliance on the threads of the fitting for sealing can also result in extensive swelling of the associated female port. The distortion of the female port, in turn, adversely effects close tolerances maintained on adjacent hydraulic components such as valve spools, plungers, and the like. Yet another problem associated with reliance on the pipe threads for sealing capabilities is the limited adjustability of the assembly.
According to the second system, a fitting incorporates an elastomeric O-ring for sealing purposes. In this arrangement, the fitting is defined by a straight boss that is adjustable because of the use of the sealing O-ring. Although this may resolve some of the adjustability problems encountered with a fitting that relies on the pipe thread for sealing purposes, it is not deemed to be applicable to higher pressures. The diameter of undercut of the threaded boss fitting determines the effective pressure area. Therefore to reduce the forces imposed on the fitting, it becomes necessary to reduce the thread size. This leads to a weaker cross-section of the fitting body because the fluid passageway must be maintained for predetermined flow requirements. Thus, although it may appear that merely increasing the undercut diameter and thread size would provide sufficient strength to the arrangement, it necessarily results in an increased area on which the pressure acts. Thus, a mere increase in size results in an increased force that tends to urge the fitting from the associated port.
It has thus been deemed desirable to provide a port fitting assembly that eliminates the swelling problems associated with some arrangements, can handle higher pressures, and yet is simple, reliable, and effective.