Seal Assembly With Radially Undulated Sealing Element

It has heretofore been known to provide a seal assembly comprising a seal element carried between two concentric metal rings wherein the seal element extends beyond the ring surface on both sides. Such seal element has consisted of a spirally wound toroid of seal material which is axially corrugated. Such an assembly is shown in a brochure of the firm KSA Dichtungssysteme GmbH and Co., of W. Germany. The brochure is entitled "Sealing Precision--The Concept from One Hand" and contains diagrams of a "Series MD 6000" which illustrates and briefly describes the above combination. It has likewise been known to provide a seal assembly, shown in the same brochure as "Series GM 4000", consisting of a sheet metal ring having a concentric groove on each side with a rubber ring sealing element or gasket vulcanized in each groove. These elements have a ridge axially beyond the radial side surfaces of the ring and depressions into which the ridges are forced when the seal assembly is compressed between opposed surfaces of assembled components.

The prior art has certain drawbacks in that the spirally wound toroid is limited to cases of use where the area to be sealed can be properly sealed by a circular seal. Further, it is not possible to properly measure the compression induced in the seal by assembly of components on each side because there is no vacant space provided into which the seal material can be compressed within the confines of the thickness of the carrying rings. Accordingly, alignment faults can occur when using components screwed or bolted together. Additionally, where high pressures are involved sealing problems may occur. Also, such seals are relatively expensive.

The present invention eliminates these drawbacks by providing a convoluted or undulating sealing ring so fashioned that passages registering between assembled components which are to be sealed against leakage are within loops or undulations of a sealing ring so that individual sealing to a large extent can be effected. On the other hand, the prior art arrangements wherein a sheet metal ring is provided with a concentric groove on each side in which is vulcanized a rubber gasket there is the expense of vulcanization on two sides of the ring and thus relatively high production costs. Further, due to the fact that the grooves are fairly shallow recesses, only a limited space in which to displace the compressed ribs or ridges of the extending portion of the seal is provided. Thus, the amount of material that can actually be used for the purposes of being compressed to form a tight seal is limited. The present invention overcomes the drawback just described by providing a seal of material disposed entirely through the thickness of the carrying rings. Accordingly, the space to take the displacement of the extending portions of the sealing ring can be made larger and therefore the compressed portion larger accordingly.

Thus, by making a seal assembly comprised of inner and outer carrying rings radially spaced to effect a convoluted channel has the advantage of providing for a certain perimeter of sealing for individual passages but can take advantage of a crest and valley design for the sealing material contour which effects a better seal by way of greater compression during assembly of the components having registering passages which are to be sealed.

The particular arrangement provides for a compression stress on the sealed material limited by the thickness of the carrying rings so that the sealing material is not subjected to any undesired stress. The carrying rings may be simply stamped parts and the sealing material such as rubber or the like molded between the rings in the convoluted channel in accordance with methods well known. The particular seal assembly herein described is especially suitable for sealing registering pressure channels of the components of a radial piston pump. Thus, in a radial piston pump the major components are the pump housing and the pulsator outlet chamber for the outlet pressures of the several piston chambers in the pump body. Thus, each component has certain passages which must register with passages of the other component and when the components are screwed or bolted together the passages must be well sealed. This has heretofore been done by individual "O" rings in grooves for each sequence of registering passages. Such arrangements, however, were relatively expensive compared to the present invention and occasionally leakage could develop due to inadvertent omission of a single "O" ring. Such drawbacks are clearly overcome by the present invention in the use of a continuous ring of convoluted contour wherein each sequence of registering passages is looped by sealing material effecting an interface and all such passages are within the interior of the convoluted ring. Thus, the inner carrying ring is provided with passages that register with the registering passages of the pump components. On the other hand, the exterior carrying ring is provided with apertures through which assembled bolts or screws may be set for screwing the pump components together and which latter passages need not be sealed and are exterior of this convoluted sealing ring.

A detailed description of the invention follows in conjunction with the appended drawing in which:

FIG. 1 is a plan view of the seal assembly;

FIG. 2 is an enlarged section on line II--II of FIG. 1; and

FIG. 3 is a longitudinal section of a multipiston radial pump utilizing the seal assembly.

Referring to FIGS. 1 and 2, the seal assembly 1 comprises means, e.g., rings 2 and 3 which may be stamped sheet metal, the rings being concentric, there being an outer ring 3 and an inner ring 2, radially spaced so as to effect a channel 4 therebetween. The rings are carrier or confining rings for a sealing material. The channel is convoluted or undulated as shown, having radially convex portions in the outer ring 2 and radially concave portions in the inner ring 3. The channel holds a sealing element of compressible material such as a sealing ring 5 of rubber vulcanized in place.

The sealing ring 5 fills channel 4 and extends axially outward of the thickness of the carrier rings at each side, with a rib or crest 6, 6A, which are enlarged portions beyond the side radial surfaces of the rings which are of equal thickness. Thus, sealing ring 5 which may be molded into place between the carrier rings is formed on the mold with the same undulating contour as channel 4, and with a continuous cross-section of the extending convexities or crests 6, 6A together with adjoining depressions, i.e., concavities or valleys 9, 9A which effect hollows below the faces of the carrier rings, within the thickness thereof. The valleys adjoin the crests and are for the purpose of accomodating displacement of the compressed material of the crests under assembly pressure between components having registering passages to be circumferentially sealed by the seal assembly of the invention as an interface therebetween.

Thus, upon compression between opposed surfaces of assembled components, the sealing material is compressed into the planes of the carrier rings.

For such purpose the inner carrier ring 3 is provided with flow passage apertures 7 that align with respective registering passages of assembled components, thus a sequence of passages for flow from one component to another has an aperture 7 for connection therebetween, as will be apparent from FIG. 3, to be later described.

In particular, it should be noted that the apertures 7 are within the confines of the continuous sealing ring 5, having a loop of convoluted shape radially convex and embracing respective apertures 7. Thus, the passage connections are well sealed exteriorly.

The outer carrier ring 2 has bores or apertures 8 for passage of screws or bolts to secure components in assembly. Such bores are for compactness located peripherally close to passages 7 and the radially concave convolutions of the sealing ring 5 embrace them.

Accordingly, the unique shape of the sealing ring 5 permits an assembly of components to be of compact design.

Referring now to FIG. 3, a radial piston pump is shown having the seal assembly 1 of the invention, and for which the invention is particularly advantageous.

In this instance, a radial piston pump supplies two oil circuits, one of which is connected to a two-cylinder pump 10 and the other circuit to a six-cylinder pump 11, all within the pump housing. A drive shaft 12 carries a cam 13 which operates the two pistons 14 of the pump 10 as well as the six pistons 15 of the pump 11. The cam 13 rotates in a cam chamber 16 which is connected with an intake 18 by way of annular groove 17. Each of the six pistons 15 sucks the pressure oil from the cam chamber via inlet passages 20 and pumps it via a pressure duct 21 and a respective outlet valve 22 into the pulsator chamber 23. Flow connects, as will be understood, via an outlet 24 with a consumer device, not shown. The pulsator chamber 23 is conventional for smoothing out the pressure pulsations occurring in the pump 11, which pulsations otherwise could possible cause roughness of system operation. The two pistons 14 of the pump 10 suck in pressure oil via respective chambers 25 adjacent the pistons 14, during the suction strokes, via suction duct 26 having the intake 18. An outlet 27 of pump 10 is connected with an additional consumer device.

The preceding description is of a conventional pump, except that the seal assembly 1 of the invention is shown as an interface between the pump housing 19 and the pulsator chamber 23 with the apertures 7 aligned with the outlet pressure ducts 21. The crests 6, 6A are of sufficiently soft material so as to be compressed during pump housing assembly to the pulsator chamber 23, for spreading into the valleys 9A, 9, respectively. Thus, the crests 6, 6A are flattened into the thickness of the rings 2 and 3 and, under such compression, elastically seal the pulsator chamber and pump housing in assembly and the several passages and components therein against leakage effective against high pressures.

The arrangement provides for considerable compression of the sealing material to effect a tight seal around the flow passages for high pressures. Also, the suction ducts 26 with their respective ball valves 28 for pump 10 are advantageously enclosed within the sealing ring 5 by the radially convex convolutions 5A.