T 0904/07 04-02-2009

1. The patent relates to an aircraft brake having discs which rotate together with the wheel and which are inter-layered with stationary discs to form a stack. An actuator located at one side of the stack extends a ram to urge the rotary and stationary discs into contact, thereby providing braking. It is stated in the patent specification that in previous arrangements of this type the actuator could not be removed without dismantling the brake assembly. As a result, failure of an actuator would result in withdrawal of the aircraft from service for the period necessary to dismantle and re-build the assembly. In accordance with the patent the actuator is mounted as a unit for ease of replacement.

2. Claim 1 specifies an aircraft brake for a wheel and brake assembly, comprising inter alia an actuator. The subject-matter of claim 8 is a wheel and brake assembly comprising a wheel and a brake "as set forth in any one of claims 1 to 5" and so includes not only the actuator specified in claim 1 but additionally a wheel and therefore is more restricted than the subject-matter of claim 1. Claim 14, on the other hand, specifies only an actuator module "for the wheel and brake assembly of one of claims 8-13", the actuator having features identical to those set out in claim 1. It follows the subject-matter of claim 14 is broader than that of either of claims 1 and 8. Claim 6 relates to a method of replacing an actuator having the same features as are specified in claim 14. Claim 14 therefore is the broadest definition of subject-matter and the most appropriate starting point for consideration of novelty and inventive step.

3. Of the evidence present in the proceedings prior to the appeal being filed, the appellant has referred to only D1. The board is satisfied that D1 is the most relevant of that evidence and forms the closest state of the art for judging novelty and inventive step of the subject-matter of claim 14.

3.1 D1 relates to a disc brake system for automotive applications in which an electrical actuator is mounted on the brake calliper. The actuator takes the form of an electric motor mounted with its rotary axis orthogonal to the rotary axis of a rotary-to-linear motion converter which is driven by the motor via a worm gear. The motor and worm gear are contained in a housing which is attachable by bolts to the calliper. The rotary-to-linear motion converter takes the form of a ball screw engaged with a nut which forms a piston or, in the terminology of present claim 14, a "ram" located in a bore in the calliper and guided by a series of rollers and balls which react transverse loads and prevent the piston from rotating in the bore. According to column 2, lines 64 to 66 the actuator is provided as a sub-assembly, thereby "making the mass-production and maintenance characteristics favourable", and is illustrated in figures 1, 2 as being mounted by three bolts accessed from one side of the calliper. However, the presence of the series of balls and rollers would render the attachment of the sub-assembly nevertheless a somewhat delicate operation since they would need to be introduced into the bore whilst offering up the actuator.

3.2 In the board's judgement the actuator of D1, although disclosed in combination with a calliper brake is suitable for an aircraft brake comprising a brake disc stack and the respondent has provided no explanation why this would not be so. In the illustrated embodiment of D1 it appears that it may be difficult to access the illustrated hexagonal socket head of the uppermost bolt for mounting the actuator to the brake head, thereby, in the respondent's view, putting into question whether the actuator may be mounted as a sub-assembly in the manner taught in the description. However, the teaching of the description, even if it were inconsistent with the drawings, is clear in itself such that the skilled person would have no difficulty in putting it into practice. Moreover, as may be seen from figure 2, the socket is only partly obscured and since a hexagonal key of appropriate design need not approach the socket axially, it is not apparent that there is, in fact, any inconsistency between the respective teachings of the description and the drawings. The respondent argues that the actuator illustrated in D1 would not be removable "as a unit" from the brake head because it first would be necessary to remove the cover to provide access to the uppermost bolt. As already explained above in respect of the matter of access to the uppermost bolt details derivable from the figures do not put into question the clear teaching of the description. Moreover, the phrase "as a unit" in claim 14 is to be interpreted in the light of the patent specification taken as a whole. In this respect the board notes that according to the description it is intended that this phrase should not exclude removal of a ram pad from the inboard end of the ram before the actuator is removed from the brake head (column 7, lines 20 to 27).

4. The subject-matter of claim 14 therefore differs from the disclosure of D1 by the feature that the ram is guided in the housing of the actuator module. This has the effect that the actuator is a self-contained unit whose function could be tested before being fitted to the brake.

4.1 The appellant argues that the skilled person faced with the problem of introducing the balls and rollers when assembling the actuator to the brake calliper would, on the basis of his general technical knowledge and without the need for inventive activity, provide a projecting sleeve on the actuator housing to retain the balls and rollers. The board disagrees with that point of view. The general technical knowledge of the skilled person is normally represented by encyclopaedias, textbooks, dictionaries and handbooks (see T 890/02, OJ EPO 2005, 497). In the present technical field it would extend also to knowledge of commonly employed mechanisms and technical equivalents of commonly known elements. None of those definitions of the general technical knowledge of the skilled person lends support to the appellant's view that the subject-matter of present claim 14 is obvious. Indeed, what the appellant argues as being within the normal design freedom of the skilled person would in fact require a radical departure from the teaching of D1 in that the projecting sleeve would need to accurately engage with the brake calliper for transfer of the transverse loads. Considerations of overall size, weight and cost thus would hardly encourage the skilled person to adopt such a change.

5. The appellant also referred in its statement setting out the grounds of appeal to evidence D9 to D12. In accordance with Article 12(4) RPBA (OJ EPO 2007, 537-547) everything presented by an appellant in its statement setting out the grounds of appeal shall be taken into account by the board "without prejudice to the power of the Board to hold inadmissible facts, evidence or requests which could have been presented … in the first instance proceedings".

5.1 The appellant argues that it was motivated to search for further evidence by the interpretation given by the opposition division to claim 18 as granted, namely that it implied that the actuator module would operate to reciprocate the ram without being mounted on the brake. This is the effect achieved by the feature which now has been included in the corresponding claim 14 that the ram is guided in the module housing. It was first argued by the respondent (patent proprietor) that claim 18 as granted should be interpreted in this way in a letter received at the EPO on 16 November 2006, which was after the date on which the appellant admits to have become aware of D9 to D12. The appellant nevertheless made no attempt to introduce the evidence D9 to D12 during the subsequent final month of opposition proceedings. The evidence D9 to D12 therefore could have been presented during first instance proceedings and so may be admitted at the board's discretion. It is established case law of the boards that one consideration in deciding how to exercise such discretion is the relevance of the evidence.

5.2 D9 relates to an alleged public prior use of an actuator. However, there is insufficient substantiation regarding its availability to the public. D10 relates to an electrical actuator for a disc brake in which the ram is the reverse construction of that in D1, whereby the nut is formed by the rotor of the motor and the piston is prevented from rotating relative to the actuator housing by its engagement with the backing plate of the brake pad. D11 was published after the priority date of the present patent and was cited only in respect of novelty in accordance with Article 54(3) EPC 1973 of the claims as granted. The appellant has not suggested that D11 would be detrimental to novelty of the present claims. D12 relates to a conventional braking arrangement in which the actuator is integrated into the brake head and therefore would not be considered relevant by the skilled person seeking to solve the problem addressed by the present patent.

5.3 On the basis of the foregoing the board concludes that none of D9 to D12 is of sufficient relevance to the present procedure to warrant further consideration. The board therefore exercises its discretion in accordance with Article 114(2) EPC 1973 and disregards this evidence.

6. It follows from the above considerations that the subject-matter of claim 14 involves an inventive step (Article 56 EPC 1973). The same conclusion is applicable also as regards claim 6 which relates to a method which requires the existence of an actuator having the same features as are specified in claim 14. Similar considerations apply also in respect of claims 1, 8, see point 2 above, and dependent claims 2-5, 7 and 9-13.