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Wednesday, 6 April 2011

IP for the immature: Putzmeister vs. Schwing and the Bastardring


The tragedy unfolding in Fukushima is no laughing matter, but some could not hide a chuckle when it was announced that giant concrete pumps known under their brand name "Putzmeister" were sent to Japan to pour water on the damaged reactors, or, as some have re-phrased it, squirt liquid over the hot core.


The IP angle to the story comes into play when we learn that Putzmeister was sued by their biggest competitor Schwing GmbH over a seal technology referred to as the "Bastardring" (Schwing GmbH vs Putzmeister AG, 305 F.3d 1318). The case involved issues of claim construction regarding Schwing's US patent RE 32,657 "Two-cylinder pump for heavy flowable materials, such as concrete".

Pumping highly viscous material such as concrete over great distances requires a lot of pressure, and correspondingly strong seals. Schwing’s ’657 patent discloses a concrete pump in which the tight metal-to-metal seal between the cutting ring and the face plate is maintained by the use of a flexible elastic ring that is compressed between the cutting ring and the shutter mechanism, shown below in cross-section in Figure 4 of the ’657 patent.
The flexible elastic ring 23, located between shutter mechanism 3 and cutting ring 14, serves as a spring that pushes the cutting ring 14 tightly against the face plate. When the pump is assembled, the flexible elastic ring is mechanically pre-stressed. As the surfaces of the cutting ring and the face plate wear away, the compressed flexible elastic ring expands axially to compensate for the wear, thereby maintaining a tight seal between the cutting ring and the face plate. In order to prevent the flexible elastic ring from being dislodged from its seating by the intense compression of the parts, the ’657 patent discloses the use of an annular extension 33 on the cutting ring 14, and a corresponding annular extension 34 on the shutter mechanism 3, to hold the flexible elastic ring in place.

In 1989, Schwing and Putzmeister settled an infringement dispute regarding the ’657 patent by entering into an agreement in which Putzmeister agreed to stop manufacturing concrete pumps in which the flexible elastic ring was held in place by the placement of annular extensions on both the cutting ring and the shutter mechanism. In return, Schwing agreed not to sue Putzmeister for infringement based on concrete pumps that held the flexible elastic ring in place with an annular extension on the shutter mechanism, but with no annular extension on the cutting ring. The parties also agreed that Putzmeister could optionally place a metal insert in the flexible elastic ring. Putzmeister referred to that configuration as the “Bastardring I” (in other news: someone at Putzmeister has a sick sense of humour).


And if that wasn't enough, there is a Bastardring II, as well: Putzmeister changed the configuration of its pumping technology in 1992 to the “Bastardring II.” The Bastardring II has an annular extension on the cutting ring, but not on the shutter mechanism. Instead of the annular extension on the shutter mechanism, a metal ring is embedded in the flexible elastic ring near the shutter mechanism.

Schwing claimed that the Bastardring II infringed the '657 patent. The district court entered two orders granting summary judgment in favor of Putzmeister, holding that the Bastardring II and a modified version of the Bastardring II do not literally infringe the ’657 patent because they do not have an annular extension on the shutter mechanism. It relied on prosecution history estoppel based on remarks Schwing made to overcome a rejection, and held that prosecution history estoppel absolutely barred infringement by equivalent means. The Court of Appeal affirmed in part, vacated in part and remanded:
In Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 234 F.3d 558 (Fed. Cir. 2000) (en banc), this court held that prosecution history estoppel acts as a complete bar to the doctrine of equivalents, so that a claim limitation that has been narrowed by amendment must be limited to its strict literal terms. Shortly before oral argument in this case, the Supreme Court vacated our decision in that case. Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 122 S. Ct. 1831 (2002). The Supreme Court rejected the “complete bar” approach and required instead an examination of the subject matter surrendered by the narrowing amendment. Id. at 1840. In so doing, the Court adopted a rebuttable presumption that the narrowing amendment surrendered the particular equivalent in question, and discussed several ways in which the patentee could overcome that presumption. Id. at 1842. The patentee can overcome the presumption that prosecution history estoppel bars a finding of equivalence, the Court explained, if the patentee can show that the asserted equivalent was unforeseeable, that the rationale underlying the amendment bears only a tangential relation to the equivalent in question, or that there is some other reason that the patentee could not reasonably be expected to have described the substitute in question. Id. at 1841-42.

At oral argument, Schwing contended that if we conclude that the amendment narrowed the annular extension limitations, we should remand the case to the district court to determine, in light of the Supreme Court’s Festo opinion, whether Schwing can successfully rebut that presumption. We agree with Schwing that, at least as to the modified Bastardring II device, the case should be remanded to the district court to determine, in the first instance, whether Schwing can rebut the Festo presumption. A remand is not necessary with respect to the Bastardring II device, however, because in light of the written description of the ’657 patent the embedded metal ring in the Bastardring II cannot be deemed equivalent to the annular extension on the shutter mechanism recited in claim 1.

So there you go. You're a bastard if you smirked.

1 comment:

Anonymous said...

In german, "Bastard" not only has the same meanng as in english, but is also used to mean "hybrid, cross-breed, or mongrel". Given the composite metal/rubber construction of the ring, "hybrid" appears to be an appropriate rendition here.

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