T 0854/09 11-03-2011

Reasons for the Decision

1. The appeal is admissible.

2. Background & Claim Interpretation

2.1 The patent concerns magnetic bearing devices with active magnetic bearings and a stator arranged in a stator column that supports a rotor. The main idea of the patent is essentially that the bearing device is formed from pre-assembled, pre-moulded electromagnetic and stator units, which have been inserted into the stator column. Vis-à-vis the prior art, where all components are first press-fitted into the stator column and then resin moulded, such a modular design is simpler to manufacture and is not as wasteful as only the relevant unit - and not the whole device- need be discarded if defective, specification paragraphs [0005],[0020] and [0021]. Claims are to the resultant device, and to the method of manufacture. These have now been limited to vacuum pump magnetic bearing devices.

2.2 In the independent claims this modular design concept is expressed in the requirement that the components of the units - an electromagnet with associated sensor for the electromagnet unit and a stator coil for the stator coil unit - are "mounted on a [respective] circular ... member and then coated and molded with ... a resin mold", with the units then "engaged to a cylindrical stator column in the order stated". This formulation - which is fully clear in the context of the method of manufacture of the device, is less so when used to define the device itself. Nevertheless, in particular when reading the claims together and in context, it is sufficiently clear to identify the bearing and stator units as separate, individually resin-moulded units or modules. The Board adds that the term "circular member" refers to what in the embodiments is in fact a cylindrical member, designated at 20c, 30c, 40c for the respective units in the partial sectional views of figures 2 and 3.

3. Main Request, Auxiliary Requests 1: Lack of Inventive Step

3.1 It is undisputed that E2 discloses the prior art. This document, entitled "magnetically levitated turbomolecular pumps", relates to a vacuum pump with magnetic bearings. The general design is shown in the top figure of page 4, and includes among other features a rotor with shaft rotatably supported by radial active magnetic bearings in the form of a radial electromagnet positioned at either end of what is clearly a cylindrical stator column. The electromagnets are each associated with an axially spaced radial sensor sensing radial displacement; together they can be said to constitute functional units. A stator coil is located between the two radial electromagnets and forms part of an electromotor driving rotation of the rotor.

3.2 The vacuum pump magnetic bearing device of claim 1 of the main request differs from this known device in the features indicated above in section 2.2 as defining the main concept of modularity, with the units as separate, individually resin-moulded modules.

Though it is true that functionally separate units can be identified in the top figure on page 4 of E2, it is insufficiently detailed for the Board to conclude with certainty that these are also structurally separate units. What appear to be spacers in the drawing between the functional units does not necessarily mean that the units are not in some way structurally integrated into a single body, for example by the acknowledged prior art technique of resin moulding after assembly. E2 in fact does not mention resin moulding, but it is clear from the above that the figure is open to interpretation. Consequently, E2 does not directly and unambiguously disclose separate, resin-moulded modules.

3.3 A modular design offers well-known advantages for manufacture and maintenance as outlined for example in specification paragraph [0005]. Manufacture is easier and more efficient with modules, which can be replaced if defective.

The benefits of resin moulding are not expressly mentioned in the patent specification, but are readily apparent to the skilled person: the mould insulates the electrical components and protects them from the environment while also supporting them and providing structural integrity.

The two measures and their effects are not inherently linked and can essentially be considered separately when assessing inventive step, following well-established practice.

3.4 The partial objective technical problems can be formulated for each difference as follows: for the modular design of the device it is how to adapt the design such that it allows for simpler and less costly manufacture, reduced wastage and easier maintenance. The use of resin on the other hand addresses the problem of how to protect and insulate various components of the bearing device while giving them structural integrity within the device.

3.5 Modularity is known in connection with magnetic bearing devices, with A1b, see page 98, A2, in figures 5, 9 and 10, and E14, see abstract and figure 1, each offering examples of modules. Though these documents refer to different fields of application (optical choppers, canned pumps) or do not mention any particular application (E14), the skilled person will be familiar with their content. Here the relevant skilled person is a mechanical engineer involved in the design of vacuum pumps that feature magnetic bearings as a central component. He therefore takes a particular interest in magnetic bearings and will follow developments in that wider field that may be of use in vacuum pumps.

A1b will be of particular interest to him as it shows a bearing device, albeit in an optical chopper, which has a layout that is similar to that of a vacuum pump such as in E2. That layout is basically modular with individual "magnetic bearing modules", see figure 1, identified in the text on page 98 as "front" and a "rear radial magnetic bearing module[s]", as well as a separate stator motor assembly. Each bearing module has an integrated optical sensor disk. These parts are clamped in place by means of end caps, which when removed allow them to be "slid out of the front of the housing as a unit", bottom lines on page 98. This is understood in context as meaning that when unclamped these parts can be removed as one or together (as opposed to separate disassembly of each part), not that they permanently form a unit, which would defeat the purpose of the use of modules.

3.5.1 It stands to reason that the skilled person, whose constant concerns are cost and complexity of manufacture and subsequent maintenance, will recognize in the principle of modularity underlying A1b the inherent benefits for manufacture and maintenance of a vacuum pump bearing device as in E2. He will therefore as a matter of obviousness adopt such a design for a pump as in E2, realizing the bearings and stator as structurally separate modules, that can be easily inserted and removed at will.

3.5.2 A1b provides little detail of the modules per se. However, their placement in the cylindrical space within the stator column dictates a cylindrical design. As each module per definition forms a self-contained unit, the skilled person will house it accordingly within a cylindrical housing that fits easily within the stator column.

Alternatively, he will draw on examples of existing magnetic bearing modules known to him from A2 or E14. The bearing modules in the photos of figures 5 and 10 of A2 are cylindrical, while a cylindrically housed bearing module can also be inferred from lines 40 to 43 of column 1 in conjunction with figure 1 of E14.

3.5.3 In conclusion, the features of claim 1 pertaining to modular design lack inventive step.

3.6 Resin moulding is conventionally employed in the field of electronics, including in magnetic bearing devices, and, more particularly, in vacuum pumps magnetic bearing devices, to protect and insulate vulnerable components and give them structural integrity. The patent acknowledges as much in its description of the prior art, see specification paragraph [0004] and also the Appellant's submissions in the grounds of appeal, point 18. E13 provides confirmation for vacuum pumps, see the abstract, and column 1, lines 50. That the skilled person would therefore routinely resin mould the components in a stator column of a vacuum pump magnetic bearing device such as that of E2 behoves no further comment. This feature is thus per se without inventive merit.

The only point to consider is how the skilled person might realize resin moulding in a device as in E2 but with a modular design. It makes no sense for him to resin mould once the modules are in place, as any benefits a modular design offer would then be lost. It will be immediately clear to him that the only sensible option is to resin mould the individual modules.

Alternatively, should he draw on E14 for the general design of an individual module, that document also teaches resin moulding of its components, see column 1, lines 29 to 31 ("Vergießen mit Kunststoff").

3.7 The Appellant has argued that the skilled person would be disinclined to combine a modular design with resin moulding as this would compromise the protection offered by a resin moulding against a corrosive environment. No evidence has been put forward in this regard, nor is the Board able to see how this might be so. In turbo-pumps corrosion is mainly due to leakage into the gap between rotor and stator at the point where the rotor shaft enters the stator column and it is in the gap that components are most exposed and liable to corrode. This remains so whether or not the stator column is formed of modules. Leakage from between modules within the stator column into the gap is highly unlikely. Nor does the fact that the resin is not continuous throughout the stator column mean that the components in the modules are more at risk: what matters is that they are encapsulated in resin and that is also the case for modules with resin moulding.

3.8 Summarizing, the skilled person as a matter of obviousness adopts a modular design as in A1b in order to facilitate manufacture and maintenance of a vacuum pump magnetic bearing device such as that of E2. The modules will obviously be cylindrical, with a cylindrical housing, to accommodate them within the cylindrical stator column. To protect, insulate and support the electrical components he will resin mould them as is conventional, but within their modules, as it would not make sense to do otherwise. He so arrives at the subject-matter of claim 1 of the main request in obvious manner. The Board concludes that the subject-matter of claim 1 of the main request lacks inventive step, Article 52(1) with Article 56 EPC.

3.9 The Board adds that it arrives at the same conclusion for further independent claims 2 and 7. Claim 2 basically adds a further, second radial magnetic bearing, a feature also present in E2, see the top figure on page 4. Claim 7 to the manufacturing method sets out the steps of assembling the device of claim 1 as necessarily follow from its modular design.

3.10 The first auxiliary request adds to claim 1 and claim 7 the feature that the cores and coils are superficially exposed at an inner circumferential area, taken to mean at the gap between rotor and stator. The patent itself, in specification paragraph [0004], lines 13 to 17, describes this as conventional in existing magnetic bearing devices, and the Board has not been given any reason why this should be less so if the device were modified to have a modular design. In view of the fact that the electromagnetic field is highly sensitive to the gap at the coils respectively cores and that a magnetic bearing device is a precision device it will in any case be immediately evident to the skilled person that he should keep the gap small and clear of resin. This is also what E14 teaches for its bearing module, see figure 1. The Board thus finds that the subject-matter of claim 1 of the first auxiliary request also lacks an inventive step, Articles 52(1) and 56 EPC.

4. 2nd Auxiliary Request

4.1 With respect to claim 1 as granted claim 1 of the 2nd auxiliary request specifies that the device is a vacuum pump magnetic bearing device and adds the features of superficial exposure (see above) and the axial thickness of the resin mould being slightly thinner than that of the circular member. That the patent has been concerned from the outset with bearing devices for vacuum pumps in particular is evident from the opening paragraph of the application as filed, or claims 5 and 6 as filed. Superficial exposure of the coils and cores is mentioned in paragraph [0017] and [0018] of the A publication. The final feature corresponds verbatim to the features of dependent claim 3 as filed.

Method claim 6 is amended in like manner with respect to granted claim 7.

The remaining claims remain unchanged, while the description is merely brought in line with the new claims.

The Board is satisfied that these amendments do not add subject-matter. It is also evident that they do not extend the scope of protection so that all requirements of Article 123 EPC are met.

4.2 The Board adds that the incorporation into the independent claims of the features of granted claim 3 is also not objectionable for lack of clarity. According to established case law Article 101(3)(a) EPC allows Article 84 EPC to be invoked only if a lack of clarity arises from an amendment per se, but not if it applies already against the granted patent as would be the case here. This feature is understood in the light of specification paragraph [0024] and figure 3 as referring to the small clearance delta at the end of the circular member due to the longer axial dimension of member with respect to mould.

4.3 That the subject-matter of claims 1 and 6 is novel is undisputed. All parties moreover agree that the final feature of claims 1 and 6 of the relative axial "thickness" of mould and member distinguishes the claimed invention over the closest prior art of E2.

4.3.1 As explained in specification paragraph [0024] this feature provides space between modules in the assembled magnetic bearing device for thermal expansion of the resin when it heats up during operation. This prevents it from expanding radially into the rotor-stator gap where it could cause damage or otherwise compromise operation. The associated objective technical problem can be formulated accordingly as how to reduce the effects of thermal expansion in a vacuum pump magnetic bearing device such as that of E2.

4.3.2 Though both E9 and E10 show axial clearance between resin and outer housing nothing in these documents suggests that the feature is in some way linked to thermal expansion of the resin. Both documents are in fact silent as to the exact significance of this feature.

4.3.3 Nor is there anything to suggest that this measure might form part of the relevant skilled person's common general knowledge. It cannot be equated with filling a container to just under the rim which serves the completely different purpose of avoiding liquid spilling from the top of the container.

4.3.4 The Board concludes that the subject-matter of claims 1 and 6 involves an inventive step.

4.3.5 Taking into consideration the amendments made to the patent according to the 2nd auxiliary request the Board finds that the patent and the invention to which it relates meet the requirements of the European Patent Convention, Article 101(3)(a) EPC. The patent can therefore be maintained as amended according to this request.

5. Apportionment of costs

5.1 The Appellant-Proprietor also appeals the Opposition Division's decision to apportion 50% of either Opponent's costs to the Proprietor under Article 104(1) EPC. The Division held, see point 56 of the decision, that this was justified as the Proprietor had filed a new request based on material from the description towards the end of oral proceedings, and this necessitated adjournment to allow the opponents to react and also to deal with the remaining requests.

5.2 By invoking its statutory right to oral proceedings, Article 116 EPC, a party can ensure that it is heard before any decision adverse to it is taken, Article 113(1) EPC. Oral proceedings thus provide a final opportunity to be heard and, with the pronouncement of the decision, will normally conclude the procedure. With this general purpose of oral proceedings in mind, parties should conduct themselves accordingly. Their actions should therefore not intentionally or irresponsibly jeopardize the taking of a decision at the oral proceedings.

5.3 In the present case the Appellant-Proprietor submitted new main and auxiliary requests at the beginning of the first oral proceedings held 3 July 2007 and in the course thereof amended the first auxiliary request several times, see points 1, 9, 16 and 17 of the minutes (notification of 17 July 2007). As a direct consequence of the Proprietor's filing of new requests and repeated amendment of the first auxiliary request during the oral proceedings, where further requests still needed discussion, the case could not be concluded at the first oral proceedings and a further oral proceedings became necessary. It is certainly true that the division could have used its discretion under Rule 116 EPC not to admit such a late filed request based on material from the description to ensure timely conclusion of the case, but failed to do so. Nevertheless, responsibility for filing amended requests so late ultimately lies with the Proprietor, who is taking a calculated risk.

Nor is it apparent to the Board from the file that the late filing might somehow have been justified by points newly raised by the Division or the Opponents during the oral proceedings. It was the Proprietor himself who at the oral proceedings first mentioned the feature in question - superficial exposure - and its significance, see point 14, third paragraph, of the minutes.

5.4 As the adjournment was primarily the result of the late filing of the new first auxiliary request, though it need not have been admitted, the Board finds it equitable to apportion part of the ensuing costs to the Proprietor as foreseen in Article 104(1) EPC. The Board therefore confirms the Opposition Division's decision to apportion 50% of Opponents' costs to the Proprietor. The costs concerned are those reasonably incurred by either Opponent in connection with the second oral proceedings, that is the expenses of a single representative for each Opponent preparing for and attending the second proceedings, including travel and accommodation.