Chicago Rawhide Mfg. Co. v. Crane Packing Co.
| Citation | 187 USPQ 540,523 F.2d 452 |
| Decision Date | 04 November 1975 |
| Docket Number | 74-1715,Nos. 74-1714,s. 74-1714 |
| Parties | CHICAGO RAWHIDE MANUFACTURING CO., Plaintiff-Appellant, v. CRANE PACKING CO., Defendant-Appellee. |
| Court | United States Courts of Appeals. United States Court of Appeals (7th Circuit) |
James M. Wetzel, Chicago, Ill., for plaintiff-appellant.
William E. Lucas, Charles M. Nisen, Charles F. Voytech, Chicago, Ill., for defendant-appellee.
Before SWYGERT, STEVENS and DOYLE, * Circuit Judges.
Plaintiff, the owner of a combination patent relating to a rotary seal assembly (Hatch '843), 1 appeals from a judgment holding the patent invalid as obvious. Defendant has cross-appealed, claiming that plaintiff's failure, during the prosecution of the patent application, to cite two prior patents described in its own internal memorandum as "the patents of most concern," and its use of a misleading affidavit to avoid another prior art reference, made this an exceptional case entitling it to an award of fees. Defendant has raised other issues which we do not reach because we affirm on the issue of validity.
Plaintiff does not challenge any of the findings of fact, arguing instead that the district court misapplied the law, particularly by minimizing the importance of the presumption of patent validity and of the commercial success of the patented seal. Our statement of the case is based largely on those findings and on the text of the patent.
Rotary mechanical seals are used in equipment which contains either a stationary housing through which a rotating shaft extends, or a stationary shaft about which a roller turns. In either situation, the relatively moving parts need lubrication; the rotary seal provides a leak-proof barrier which keeps the lubricant within the machine and dirt and grime out.
Years ago oil seals were nothing more than a lubricating material called a "packing" crammed in a "stuffing box" which surrounded a shaft. Such packing needed frequent replacement, tended to leak, and was generally unsatisfactory. By 1961, when plaintiff's Hatch device was developed, the rotary seals in common use were more complex. Typically they included four features worthy of separate mention.
(1) The primary seal enclosing the lubricant was affected by engaging a sealing ring (which might rotate with a shaft) with a mating ring or mating surface (which might be affixed to the stationary housing). (2) The sealing ring, and sometimes the mating ring as well, was provided with a spring means which applied pressure in an axial direction i. e., parallel to the rotating shaft to maintain the sealing ring in "end face" running engagement with the mating surface. (3) An interlocking means transmitted driving torque to the sealing ring. And finally (4), a secondary seal protected the spring and the interlock from outside dirt. From even this abbreviated description it is evident that such seals required a multiplicity of parts. 2
In 1959, Caterpillar Tractor Company began to use a much simpler and more durable seal called the Duo Cone. The Duo Cone used neither a spring means to apply pressure to the sealing ring in an axial direction (or to the mating ring or surface) nor any mechanical interlock to attach the ring to the shaft. Instead, Caterpillar shaped the back of the sealing ring (and also the back of the mating ring) more or less like an irregular, horizontal "V," to receive a doughnut shaped rubber ring (a "torus") in such a way that pressure against the rubber ring would simultaneously apply axial force to push the rings together and also radial force affixing the sealing ring to the shaft and the mating ring to the housing. The separate parts which previously formed an axial spring, a radial interlock, and a secondary seal, were all replaced by a simple rubber torus which, when compressed, continuously applied the requisite force to hold the ring in place.
The Hatch seal, invented in 1961, was also a simple combination of a metal ring and a rubber ring. Unlike the Duo Cone seal, however, the rear of the metal ring contained a right angled seat and a cross section of the rubber ring was shaped like a parallelogram rather than a circle. Compression of the rubber ring, upon installation, pressed the metal ring in an axial direction against its opposing radial face to form the primary seal and also provided the torque to cause rotation. The invention covered both a single face seal including one metal ring and one rubber ring and a double face seal consisting of two identical seals mounted with their metal rings face to face. 3
The specifications in the Hatch patent primarily emphasize the advantages of using the simple rubber ring to perform three entirely different functions previously performed by three different elements in the rotary seals then in common use. 4 Essentially the same advantages were achieved by the Duo Cone seal which was described in the patents owned by Caterpillar Tractor Company. 5
The district court's conclusion that the Hatch invention was obvious was reached after making an accurate and detailed determination of the scope and content of the prior art, considering the differences between that art and the Hatch claims, and concluding that the level of skill in the rotary seal art was "quite high" at the time of the Hatch invention since both plaintiff and defendant were then aware of the advantages of the Duo Cone assembly.
The district court found that the basic elements of the Hatch device were disclosed by the prior art. The concept of a simple juxtaposition of a rubber ring and a metal sealing ring with compression upon installation providing both axial and radial force and also performing the secondary sealing function was revealed by Duo Cone. Combinations of a metal ring containing an angled rear seat with a rubber washer shaped like the one used by Hatch had been used on more than one occasion before. 6 Indeed the rubber ring with a cross section resembling a parallelogram a frusto-conical shape had even become known as a "Belleville washer." Based on the prior use of such a washer and a right angled rear seat on a metal ring, together with the simple concept illustrated by Duo Cone, the district judge concluded that the Hatch patent lacked the inventiveness required by § 103; he said that the determination of obviousness was "based on clear and convincing evidence."
The Hatch device enjoyed prompt and widespread commercial success. The district court discounted the significance of this success, however, because Caterpillar had refused to grant a license to manufacture the Duo Cone seal, and apparently had limited its use to Caterpillar's own heavy equipment. The district court drew the inference that the demand for the Hatch device would not have been so high if Caterpillar had commercially marketed Duo Cone. Plaintiff criticizes the district court's analysis as inadequately supported by the record and as contradicted by evidence identifying superior features of the Hatch device, particularly its efficient installation.
The district court refused to find plaintiff guilty of fraud on the Patent Office either because of the failure to cite pertinent prior art or because of the somewhat misleading character of an exhibit attached to an affidavit submitted by one of the inventors.
A patent issued in 1958 (Payne '226) taught the use of a mating ring supported upon a frusto-conical member. 7 This was the first patent discussed in detail in the district court's analysis of the prior art. 8 It was one of two patents which one of the inventors of Hatch described, before the Hatch application was filed, as "the patents of most concern." Unquestionably it was relevant prior art, but it was not cited to the Patent Office. Without condoning plaintiff's omission, and after stating that it considered this a "close case," the court declined to find fraud because another somewhat similar Payne patent had been cited and the omission of Payne '226 appeared to be an unintentional isolated act.
Prior to issuance, the Hatch claims had been rejected on the basis of an earlier patent, Krug '274. Krug had disclosed a seal in which compression of "a centrally apertured connecting disc" composed of synthetic rubber material applied axially directed force against a metal sealing ring. 9 In order to avoid the Krug reference, one of the inventors of Hatch prepared an affidavit describing tests comparing the flexibility of the Krug disc and the Hatch frusto-conical washer. An exhibit to that affidavit contained a pictorial representation of the Krug installation which made it appear that the unconfined portion of the rubber disc was significantly greater (and presumably, therefore, more flexible) than it actually was in the test model used by the affiant. However, the actual dimensions of the test device were accurately set forth on the exhibit and a careful examination of the diagram would have revealed its distortion. For this reason, together with a reluctance to infer that the Patent Examiner actually relied on tests of only one device when the Krug patent made it clear that variations in construction would produce variations in actual pressure, the district court refused to find that the affidavit was fraudulent.
Defendant's accused device was first marketed in 1970. Apparently initial attempts to make a seal using a Duo Cone metal ring and a rubber ring shaped like a doughnut with an axial lip on it failed. Later defendant copied plaintiff's metal ring with a right-angled rear seat and substituted a washer with a cross sectional appearance only slightly different from a parallelogram. Defendant's theory of non-infringement, rejected by the district court, was that plaintiff's claims were limited to the precise parallelogram shape and, further, that pressure on defendant's washer produced more of a rolling action than spring-like compression. In any event, we do not reach...
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