1. Field of the Invention
This invention relates generally to hydraulic seals and more particularly to a novel single apex full width two element high and low pressure seal assembly.
2. Prior Art
In the past, it has been common to provide two or more part seals for hydraulic and pneumatic use wherein the seal assembly is placed in a standard groove of one machine part to project toward and engage a second relatively movable machine part, the object being to prevent fluid displacement across such sites. The use of such multi-part seal assemblies of the prior art has often resulted in misorientation, twisting and extrusion of the yieldable sealing element so that the initial fluid-tight relationship is lost. Thus, such prior art proposals have regularly experienced seal failure because of lack of resistance to pressures imposed upon the seal. Wide contact dynamic seal areas proposed in the past provide at best limited pressure resistance to fluid displacement across the seal and at the same time cause an increase in frictional resistance to displacement of the two machine parts. These types of seal assembly configurations commonly permit an unacceptably high level of fluid leakage across the seal site.
In addition, specially configurated and expensive machine part grooves and seal assembly components are frequently required. Often, a plurality of seals or a plurality of seal assemblies or a plurality of dynamic seal areas are required between machine parts, which introduce complexity and cost factors which make production prohibitive. Many such prior art seal proposals commonly loosen with wear and often the two elements of the seal assembly are relatively instable one in respect to the other. Thus, each of the two seal members will displace relative to the other during use.
Examples of broad seals which result in limited resistance to fluid displacement with increased friction and wear and across which leakage often occurs, somtimes at high pressures and nearly always at low pressures are U.S. Pat. Nos. 3,636,824; 3,149,848; and 3,418,001. The first mentioned patent also is an example of plural seal assemblies being required between machine parts. U.S. Pat. No. 3,268,235 is an example of requiring a plurality of spaced sealing surfaces, interrupted in each instance by a groove.
Examples of instability between the two seal elements of the seal assembly are found in U.S. Pat. Nos. 3,328,041; 2,931,673; Re 24,440; 3,663,024 and 2,877,070. U.S. Pat. No. 3,418,001 also comprises a two-part seal assembly where the two parts do not work substantially in unison but rather may be independently displaced. U.S. Pat. No. 3,663,024 also illustrates a spring-loaded triangular seal, where the two parts thereof are allowed to respond during use substantially independent of each other.
In addition, it has sometimes been proposed that the sealing element be supported not only by the second element but also upon shoulders in the one machine part directly adjacent to the machine groove. See U.S. Pat. No. 3,814,445. Further, somtimes unusually configurated grooves possessing special structural characteristics for retaining the seal assembly have been proposed. See U.S. Pat. No. 2,915,349.