UNITED STATES PATENT AND TRADEMARK OFFICE BEFORE THE BOARD OF PATENT APPEALS AND INTERFERENCES

Transcription

1 UNITED STATES PATENT AND TRADEMARK OFFICE BEFORE THE BOARD OF PATENT APPEALS AND INTERFERENCES Ex parte HUBERTUS BUTTNER, MARCUS VAN HEYDEN, MARKUS DEUTEL, and ALFONS VOLLMUTH Appeal Technology Center 2800 Decided: November 24, 2009 Before JOHN C. MARTIN, JOSEPH F. RUGGIERO, and MAHSHID D. SAADAT, Administrative Patent Judges. MARTIN, Administrative Patent Judge. DECISION ON APPEAL 1 The real party in interest is ZF Friedrichshafen AG.

2 STATEMENT OF THE CASE This is an appeal under 35 U.S.C. 134(a) from the Examiner s rejection of claims 1, 2, and 4-14, which are all of the pending claims. We have jurisdiction under 35 U.S.C. 6(b). We reverse. A. Appellants invention 2 Appellants invention relates to a rotor for an electric machine (Specification 0001) and more particularly to stiffening the rotor without the use of additional elements. Id. at Figure 1 is reproduced below. 2 References herein to Appellants Specification are to the application as filed rather than corresponding Patent Application Publication 2006/ A1. 2

3 Figure 1 shows an axial cross section through a preferred embodiment of a synchronous machine having a cup-shaped rotor 12 that encloses a stator 14, which is shown only in schematic fashion. Id. at Rotor carrier 16 has a cylindrical axial support portion 18 extending axially with respect to the axis of rotation A and a radial support portion 20 that connects the carrier to shaft 19. Id. The cylindrical axial support portion 18 holds in its interior a conventional stamped sheet pack 24 consisting of a plurality of lamellar sheets (22 in Fig. 2). Id. The inside 3

4 circumferential surface of the sheet pack 24 carries a plurality of permanent magnets 26. Id. Figure 2 is reproduced below. Figure 2 is an enlargement of the circled portion of Figure 1. Id. at The sheet pack 24 is initially attached to the support portion 18 in the conventional manner by pressing, shrink-fitting, adhesive bonding, or the like. Id. at To achieve an especially firm arrangement which stiffens the rotor 12, welds 30 and 32 are provided at the end surface 28 of the rotor 10 facing away from the radial support portion 20. Id. The first weld 30, which can be in the form of individual sections but is preferably in the form of a closed ring, extends within the radial dimension of the sheet pack 24 and at a predetermined distance away from the attachment area 34 where the sheet pack 24 is attached to the cylindrical 4

5 axial support portion 18. Id. In addition, the first weld 30 is located at predetermined distance (i.e., a least three mm) from the surface opposite to cylindrical axial support portion 18, i.e., at predetermined distance from the inner peripheral surface of the sheet pack. Id. at At this distance, the electrical field induced in the sheet pack by the stator winding is relatively weak, as a result of which the lamellar sheets that have been electrically short-circuited by the weld 30 represent only a negligible source of parasitic eddy currents. Id. The efficiency of the electric machine is therefore not significantly affected. Id. The depth of weld 30 is described approximately 4-6 mm in the axial direction (id. at 0021) and also as approximately 3 mm (id.), thereby connecting a plurality of lamellar sheets 22 to each other. Id. A second weld 32 of approximately the same depth or length as weld 30 attaches the sheet pack 24 to the cylindrical axial support portion 18 of the rotor carrier 16. Id. at This weld 32, too, can be in the form of individual sections or can be closed and continuous and thus extend around the entire circumference. Id. B. The claims The sole independent claim before us is claim 1, which reads: 1. A rotor for an electric machine comprising: a rotor carrier comprising a cylindrical axial support portion extending axially with respect to an axis of rotation of said rotor; 5

6 a sheet pack comprising of a plurality of lamellar sheets, said sheet pack being attached to said axial support portion at an attachment area, said sheet pack having an inside circumferential surface radially opposite from said attachment area; and a first weld formed in said sheet pack at a predetermined radial distance away from said attachment area and at a predetermined radial distance away from said inside circumferential surface, wherein said first weld extends axially into said sheet pack through only some of said lamellar sheets. Claims App., Br. 9. C. The references and rejections The Examiner relies on the following references: Yamada et al. ( Yamada ) US 5,942,831 Aug. 24, 1999 Nakahara et al. ( Nakahara ) US 7,049,726 B2 May 23, 2006 Arimitsu et al. ( Arimitsu ) US 7,138,742 B2 Nov. 21, 2006 Claims 1, 2, 4, and 6-14 stand rejected under 35 U.S.C. 103(a) for obviousness over Arimitsu in view of Yamada. Final Action 2. Claim 5 stands rejected under 103(a) for obviousness over Arimitsu in view of Yamada and Nakahara. Id. at 7. THE ISSUES Appellants have the burden on appeal to show reversible error by the Examiner in maintaining the rejection. See In re Kahn, 441 F.3d 977, (Fed. Cir. 2006) ( On appeal to the Board, an applicant can overcome a 6

7 rejection by showing insufficient evidence of prima facie obviousness or by rebutting the prima facie case with evidence of secondary indicia of nonobviousness. (citation omitted)). The dispositive issue raised by Appellants arguments is whether Arimitsu and Yamada collectively suggest locating a weld in the claimed position in the rotor, i.e., at a predetermined radial distance away from the attachment area (i.e., outer peripheral surface) of the rotor and at a predetermined radial distance away from the inside peripheral surface of the rotor. ANALYSIS Arimitsu discloses a rotating machine employing laminated sheets to form the rotor or stator. Arimitsu, col. 1, ll Figure 3 is reproduced below. 7

8 Figure 3 is a longitudinal cross-sectional front view of Arimitsu s first preferred embodiment of a plural-axis multilayer motor M, which is shown in Figure 1. Id. at col. 2, ll The motor includes an inner rotor IR, a stator S, and an outer rotor OR (id. at col. 2, ll ), of which the Examiner relies on outer rotor OR. Outer rotor OR has a laminated rotor base 60 that carries twelve magnets 61. Id. at col. 4, ll The outer peripheral surface of outer rotor OR is fixed to an outer rotor casing 62 by means of a brazing or adhesion. Id. at col. 3, ll Figure 5, which shows welds but is not relied on by the Examiner, is reproduced below. 8

9 Figure 5 is an explanatory view depicting weld portions in the outer rotor and inner rotor in the first embodiment of motor M. Id. at col. 4, ll The laminated steel sheets that form the rotor base (60 in Fig. 3) of outer rotor OR are united by three laser weld portions 91 that extend in an axial direction at 120 degree intervals on the outer peripheral surface of the outer rotor base and face the inner surface of the outer rotor casing (62 in Fig. 3). Id. at col. 4, ll Inner rotor IR has similar weld portions 90. The axial length of weld portions 91 is depicted in Figure 2, which is reproduced in part below. 9

10 Figure 2 is a longitudinal cross-sectional side view of a portion of the first preferred embodiment of motor M. Id. at col. 2, ll As shown in this figure, weld portion 91 extends along the entire axial length of the outer peripheral surface of the outer rotor base (60 in Fig. 3). It is apparently because weld portions 91 lie on the outer peripheral surface of the outer rotor base rather than being located between its inner and outer peripheral surfaces, as required to satisfy claim 1, that the Examiner instead relies on Figure 7, which is reproduced below. 10

11 Figure 7 shows caulked portions located on the outer rotor and inner rotor of the plural-axis multilayer motor in accordance with a second preferred embodiment. Id. at col. 2, ll This second embodiment replaces the laser weld portions 90 and 91 of the first embodiment with caulked portions 92 and 93, respectively. Id. at col. 6, ll In contrast to weld portions 91, which are located on the outer peripheral surface of the outer rotor base, caulked portions 93 are located at a substantially center position in the radial direction in the outer rotor base. Id. at col. 6, ll Comparing claim 1 to this second embodiment, the Examiner found that Arimitsu et al. fail to show the caulked portion is a welded portion and wherein said first weld extends axially into said sheet pack through only some of said lamellar sheets. Final Action 3. To remedy these 11

12 deficiencies, the Examiner relies on Yamada, which discloses a method of forming a plurality of laminated core units that can be reliably separated without interrupting the laser beam irradiation used to weld together the thin sheet core pieces. Yamada, col. 1, l. 65 to col. 2, l. 9. In one embodiment, this is accomplished by providing the thin sheet core pieces that are intended to serve as the top and bottom end faces of each core unit with notches that prevent the formation of welds at the locations of the notches. Id. at col. 2, ll Figure 1 is reproduced below. Figure 1 is a partial front view of a stack of core pieces that were formed in accordance with a first embodiment. Id. at col. 3, ll Notches 9 and 10, which were formed (Fig. 6) in their respective thin sheet core pieces before those core pieces and the intervening core pieces were 12

13 stacked in the welding apparatus (Fig. 2), prevent welding from occurring at those locations. Id. at col. 5, ll Consequently, each core unit 8 can reliably be separated from the subsequent core unit 8 at boundary A (Fig. 1) without interruption of (i.e., turning off) irradiation by laser beams 6 (Fig. 2). Id. at col. 5, ll Figure 4 is reproduced below. Figure 4 is a front view of one of the completed cores. Id. at col. 3, l. 17. The Examiner, apparently referring to Figure 4, characterizes Yamada s welds as extend[ing] axially into said sheet pack through only some of said lamellar sheets (Fig. 2) for the purpose of reducing cost (Col. 2, lines 1-2). Final Action 3. Before considering whether to address Appellants argument (Br. 5-6) that this is a mischaracterization of Yamada s welds, we will address the Examiner s rationale for replacing 13

14 Arimitsu s caulked portions 93 with weld portions located in the same radial positions. Specifically, the Examiner concluded that [e]ven though the spot weld of Yamada et al. produced on the outer circumference of a stator, it is also a weld to hold the sheets together and it is within a level of an ordinary skill in the [a]rt to replace the caulking (to hold the sheets together) by welding (also to hold the piece together).... (Answer 9.) We agree with Appellants that this reasoning is erroneous because [n]either Arimitsu nor Yamada suggests a rotor having a weld in the sheet pack at any distance from the inside circumference.... (Br. 6-7.) See also Reply Br. 2 ( [N]either Arimitsu nor Yamada teach how to carry out a welding process inside a sheet area or even suggest doing so. ). To the contrary, as pointed out by Appellants, Arimitsu specifically discloses that welds, when used instead of caulking, are formed on the outer peripheral surface of the sheet pack. Id. The Examiner correctly points out that Arimitsu does not indicate that welds should not be used in at the locations of the caulking portions. See Answer 9. ( Arimitsu et al. disclose weld 91 extending through all the sheets and Arimitsu et al. did not teach the weld is not desirable and should not be used. ). However, Arimitsu s failure to specifically teach away from such weld locations does not establish their obviousness. Also, while the Examiner is generally correct to characterize Arimitsu as teaching that welds and caulking are equivalent methods to hold the sheets of the core together (id. at 10), Arimitsu does not disclose or suggest that the radial locations of the welding portions and caulking portions are interchangeable. 14

15 Because we agree with Appellants that Arimitsu and Yamada fail to suggest replacing Arimitsu s caulked portions 93 with weld portions located in the same radial positions as those caulked portions, it is not necessary to address Appellants other arguments against the rejection. The rejection of claim 1 under 35 U.S.C. 103(a) for obviousness over Arimitsu in view of Yamada is reversed, as is the rejection on that ground of dependent claims 2, 4, and The rejection of dependent claim 5 under 103(a) for obviousness over Arimitsu in view of Yamada and Nakahara is also reversed. Nakahara does not cure the above-noted deficiency in the combined teachings of Arimitsu and Yamada. DECISION The Examiner s rejection of claims 1, 2, and 4-14 under 35 U.S.C. 103(a) for obviousness over the prior art is reversed. ke REVERSED COHEN, PONTANI, LIEBERMAN & PAVANE LLP 551 FIFTH AVENUE SUITE 1210 NEW YORK, NY