T 2866/18 04-10-2022

1. Main request (patent as granted) - Article 100(b) EPC

1.1 Feature "microchannels" (M1.1)

The Board agrees with the patent proprietor in that the term "microchannel heat exchangers" is common in this particular technical field when referring to a specific kind of heat exchanger comprising a plurality of parallel channels longitudinally arranged within every heat transfer tube communicating with two manifolds. The reference to "minichannels" in the patent specification cannot cast any doubt on the meaning of the feature "microchannels" to the extent of preventing the skilled person from being able to reproduce the invention. The skilled reader understands that both terms are used interchangeably (see paragraph [0003], last sentence) when referring to this specific kind of heat exchanger.

Therefore, the skilled person can implement this feature in the light of their common general knowledge.

1.2 Combination of features M1.10 ("just slightly") and M1.12 ("to minimise the likelihood")

The Board does not agree with the interpretation of the feature "to minimise the likelihood of said securing material at least partially blocking any of said plurality of channels" (M1.12) proposed by the opponent. The term "to minimise" cannot be understood as ensuring an absolute minimum, neither according to the literal meaning of the term nor when this is interpreted in the context of the patent. The skilled person would interpret "to minimise" in feature M1.12 as reducing the likelihood of blocking the channels. This implies, in the context of features M1.10 and M1.12, that a compromise must be reached between feature M1.10 (i.e. arranging the edge of the tubes as close as possible to the manifold wall) and feature M1.12 (i.e. the minimisation of the likelihood of the channels getting blocked by the securing material), something which requires that the edge of the tubes is arranged at some distance from the manifold wall.

The wording "just slightly" does not specify how far the tube extends inwardly of the manifold wall, but this does not prevent the skilled person from putting the invention into practice, since they would know how to reach the above-mentioned compromise by simple trial and error. In particular, Figure 4 and the description (see paragraph [0017]) disclose an example which would assist the skilled person in this respect.

Concerning the properties of the melting material and other undefined parameters of the brazing process, the skilled person would know how to adapt the invention to different materials and conditions in order to reach the compromise defined in claim 1. All these parameters are conventional in the field of brazing, and the skilled person is used to adapting their way of working depending on the parameters involved.

1.3 In view of the above, the ground for opposition based on Article 100(b) EPC does not prejudice the maintenance of the patent in accordance with the main request.

2. Main request (patent as granted) - Article 100(c) EPC

2.1 Feature M1.3 ("[a pair of spaced manifold structures] each having a manifold wall")

The opponent did not bring forward any new arguments concerning feature M1.3 during the oral proceedings, and declared that it maintained its position as submitted in written form.

In view of this, the Board remains of the opinion advanced with its preliminary position on the case, namely that the feature is disclosed in the originally filed application for the following reasons:

Originally filed Figure 2 concerns a heat exchanger of the prior art related to the invention (see page 2, lines 1 to 4), presenting the problem of blocked microchannels (see Figures 3A and 3B, and also page 6, lines 1 to 3 and 9 to 12). The originally filed application discloses immediately afterwards the solution for such a problem in the kind of heat exchangers disclosed in Figure 2 (see page 6, lines 29 to 31).

Since the heat exchanger of Figure 2 concerns a microchannel heat exchanger comprising two manifold structures 30, 34, each disclosing a manifold wall (see page 6, lines 4 and 5), and since the disclosed solution for the problem in such a heat exchanger comprises providing the claimed openings in a wall 56 of the given manifold structures (see page 2, line 4 to 8, and page 6, lines 29 to 31), it can be concluded that feature M1.3 has a basis in the originally filed application.

2.2 Features M1.8 (openings in manifold structures), M1.9 (deforming the material outwardly away) and M1.10 (edges of the tubes extend just slightly inwardly)

The arguments of the opponent against the use of lines 5 to 10 of originally filed page 3 as a basis for the combination of feature M1.10 with features M1.8 and M1.9 in claim 1 of the granted patent are not persuasive.

Originally filed claim 1 comprises feature M1.13 (there being modifications to at least one of said manifold structures and said heat transfer tubes), which is immediately followed by feature M1.12 (to minimise the likelihood of blocking). Both features have to be considered in combination given the causal relationship thereby defined. Thus, the reader knows that the minimisation of the likelihood of blocking results from modifications to the manifold structures and heat transfer tubes.

When reading the first section of the "Summary of the invention", the reader further learns that, according to the invention, modifications to the manifold structures (page 3, lines 5 to 6) and the heat transfer tubes (page 3, lines 6 to 8) can be provided "such that channels in the heat transfer tubes are unlikely to be blocked by brazing material during the brazing process". Given the intended interpretation of the feature "to minimise the likelihood" (see section 1.2 above), the reader will understand that the arrangement disclosed at the beginning of the "Summary of the invention" is intended to minimise the likelihood of blocking, even if it is worded differently from feature M1.12. The reader will also understand that the modifications to the manifold and heat transfer tubes disclosed in this section of the "Summary of the invention" correspond to the "modifications" of feature M1.13 which are necessary to minimise the likelihood of blocking according to originally filed claim 1.

Consequently, lines 5 to 10 of originally filed page 3 relate to an embodiment concerning the minimisation of the likelihood of blocking and can form the basis of amendments to claim 1 which are linked to this effect (defined in feature M1.12).

Thus, the content of originally filed claim 4 is not relevant to the discussion on added subject-matter.

2.3 The opponent alleges that the arguments given on page 6 of the decision under appeal concerning the basis in the application as originally filed for dependent claim 3 of the main request are not persuasive. It does not, however, provide any arguments as to why this is the case. In the absence of any substantiated reasons for requesting the reversal of the decision under appeal in this regard, the Board has decided not to take this allegation into account (Article 12(2) and (4) RPBA 2007).

2.4 In view of the above, the ground for opposition based on Article 100(c) EPC does not prejudice the maintenance of the patent in accordance with the main request.

3. Main request (patent as granted) - Article 54 EPC

The subject-matter of claim 1 differs from each of D10 and D11 in feature M1.9 ([openings formed] by deforming the material of said manifold wall of said manifold structures outwardly away from an internal passage in said manifold structures).

The opponent is right in that feature M1.9 is a "product by process" feature. Thus, in order to ascertain a difference over other products produced in a different way, a distinguishing feature must be present in the claimed product that is brought about by the production method used.

The opponent is also right in that Figure 4 of the patent specification cannot be taken as a reference as to what the resulting product should look like. The dimensions of the portions of material framing the openings in Figure 4 are approximately as long as the diameter of the opening, which does not seem compatible with a punching step. Furthermore, neither the coincident length of the framing material above and below each heat transfer tube (32, 132) nor the shape of the edges thereof fit with the lack of uniformity a punching step should entail when the manifold wall is traversed by a punch.

However, this does not mean that feature M1.9 does not imply a limitation. The formation of openings by deforming the material of the manifold wall outwardly away from the internal passage necessarily entails the presence of some of the material of the manifold wall framing the opening at the exterior side of the manifold.

Contrary to the opinion of the opponent, the figures of D10 and D11 do not disclose any material framing the openings of the manifold (D10: slits 36; D11: slits 75). Figures 1, 2, 3 and 7 of D11, where slits (75) are shown, do not clearly and unambiguously disclose such a feature. In Figure 3 of D11 it can be observed that the slits (75) are provided on an upper portion of the manifold wall formed between the grooves (74), but no framing of the openings (75) by the allegedly deformed material can be seen. It should be noted that the deformed material defined in feature M1.9 is the one resulting from the formation of the openings (feature M1.8), and not the one resulting from any other deformation (e.g. for forming the grooves 74 and the raised spaces between them in D11). The same applies to Figures 1, 7, 15 and 17 of D10, which correspond to the cited figures of D11 as far as the slits (36) and the grooves (35) of D10 are concerned (D11 uses different reference numerals).

Even though the descriptions of D10 and D11 disclose that all protrusions and openings in the manifold wall (D10: 28; D11: 70) are formed at the same time by making the manifold wall "from an aluminium brazing sheet by press work" (D10: page 24, lines 5 to 8; D11: page 25, lines 3 to 7) (emphasis added), they do not disclose in a clear and unambiguous manner that the openings are formed by deforming the material of said manifold wall outwardly away from an internal passage in the manifold structures. Thus, even assuming that "press work" excludes a cutting tool at the pressing device which could produce the openings, nothing in D10 or D11 hints at the presence of a punch which deforms the material of the manifold wall in the claimed direction.

In view of the above, the subject-matter of claim 1 is novel over both D10 and D11 (Article 54(2) EPC).

4. Main request (patent as granted) - admittance of inventive step objections - Article 13(2) RPBA 2020

4.1 In its Notice of Opposition, the opponent raised lack of novelty objections against claim 1 of the main request on the basis of documents D10 to D13. The opponent also raised an inventive step objection against claim 1 starting from document D13, in case the Opposition Division were to consider the subject-matter of claim 1 novel.

4.2 In the decision under appeal, the Opposition Division considered claim 1 of the main request to lack novelty over documents D10 and D11. The patent proprietor contested this finding in its statement of grounds of appeal. In its reply thereto, the opponent did not raise any inventive step objections against the main request. Instead, the opponent simply announced that it would comment on inventive step during the oral proceedings before the Board if the Board did not accept its view on novelty regarding claim 1.

4.3 In its communication under Article 15(1) RPBA 2020, the Board gave its reasoned preliminary opinion that, contrary to what had been held by the Opposition Division, the subject-matter of claim 1 was novel over documents D10 and D11 (section 9.3.4). The Board further noted the absence of any objections by the opponent as regards inventive step (section 9.4).

4.4 In the oral proceedings before the Board, the Board confirmed its preliminary opinion and concluded that the subject-matter of claim 1 was novel over documents D10 and D11. Subsequently, for the first time in the proceedings before the departments of both instances, the opponent raised inventive step objections starting from either document D10 or D11 in combination with any of documents D2, D5, D6 or D13.

4.5 Under Article 13(2) RPBA 2020, any amendment to a party's appeal case made after notification of a summons to oral proceedings shall, in principle, not be taken into account unless there are exceptional circumstances, which have been justified with cogent reasons by the party concerned.

4.6 As the opponent's inventive step objections were not contained in its reply to the patent proprietor's statement of grounds of appeal, raising them for the first time at the oral proceedings before the Board constitutes an amendment to the opponent's appeal case under Article 13(2) RPBA 2020 (see J 14/19, Reasons 1.4-1.8), the admittance of which is subject to the Board's discretion. Whether or not these objections stay within the same overall "factual and legal framework" is not decisive for the purpose of determining what constitutes an amendment of the appeal case under the RPBA 2020 (T 2360/17, Reasons 2.4, last paragraph). It may, however, play a role in the Board's exercise of discretion under Article 13(2) RPBA 2020 (see T 574/17, Reasons 2.3.1 and T 2920/18, Reasons 3.13).

4.7 The question of whether there has been an amendment to a party's appeal case under the RPBA 2020 has to be distinguished from the question of whether a fresh ground of opposition has been raised. Whether the documents taken as starting points for new inventive step objections were previously used for objections regarding a lack of novelty has no bearing for determining whether these inventive step objections constitute an amendment to the opponent's appeal case under Article 13(2) RPBA 2020 (see T 1042/18, Reasons 4.3-4.12; see also T 1179/17, Reasons 4.6.2; T 1816/17, Reasons 12; T 2161/18, Reasons 5.4; and T 151/19, Reasons 3.7.5). Having said that, the Board notes that combining D10 or D11 with new documents such as D2, D5, D6 or D13 also goes beyond the "factual and evidentiary framework" of the previous novelty objections within the meaning of T 184/17, Reasons 4.8.

4.8 The opponent put forward that its inventive step objections as raised in the oral proceedings before the Board were prima facie relevant. Other than that, no reasoning justifying exceptional circumstances under Article 13(2) RPBA 2020 was provided.

4.9 Although it is not a necessary precondition for a Board to assess the prima facie relevance of an objection in order to come to the conclusion that there are no exceptional circumstances under Article 13(2) RPBA 2020, the Board considered it appropriate in the present case to conduct such a prima facie assessment (see T 574/17, Reasons 2.3.3). It is noted that, in view of the Opposition Division's finding of a lack of novelty of the subject-matter of the main request, inventive step was not assessed in the opposition proceedings.

4.10 Prima facie relevance of the inventive step objections

4.10.1 The heat exchangers of D10 and D11

Both D10 and D11 concern microchannel heat exchangers comprising heat transfer tubes (D10: 4; D11: 12) having a plurality of refrigerant channels (D10: 4a; D11: 12a) extending longitudinally of the tube and arranged in parallel (D10: see Figure 3; D11: see Figure 9). Thus, when considering combining D10 or D11 with any prior-art document, it must be assessed whether or not the skilled person would regard such a combination as being compatible with the heat transfer tubes of these documents.

4.10.2 Objective technical problem starting from D10 or D11

The patent proprietor proposes as an objective technical problem "how to provide an alternative construction for heat exchangers".

The opponent argues that the objective technical problem is "how to carry out openings in order to ensure a stable connection without pressure loss".

The technical effect of the distinguishing feature M1.9 ([openings formed] by deforming the material of said manifold wall of said manifold structures outwardly away from an internal passage in said manifold structures) is that some of the material of the manifold wall will frame the openings at the external side of the manifold.

The Board sides with the opponent in that, in view of the technical effect, the objective technical problem can be defined as how to carry out openings in the manifold wall in order to provide a stable connection (because of the framing material around the opening). However, the aspect relating to a reduced pressure loss cannot form part of the problem, since feature M1.9 does not per se define any limitation that would relate to this effect.

4.10.3 Combination of D10 or D11 with D2

The opponent refers to Figure 3 of D2 in support of its arguments.

However, this figure (reproduced below) does not disclose in a clear and unambiguous manner that the opening is formed by deforming the material of the manifold wall since the portions of material framing the opening are very small with respect to the diameter of the opening. Consequently, the opening of Figure 3 appears to have been produced by means other than deformation, such that the edge of an already existing opening is later deformed in a further step.

FORMULA/TABLE/GRAPHIC

As D2 does not disclose feature M1.9 at first sight, the objection based on a combination with this document is not prima facie relevant.

4.10.4 Combination of D10 or D11 with D5

The opponent argues that Figure 6(b) of D5 discloses the distinguishing feature.

However, Figure 6(b) is just one out of three embodiments disclosed in Figure 6 (reproduced below), all of which form part of the prior art discussed in D5 (see paragraph [0004] of the translation which was included in D5). Figure 6(a) discloses an embodiment where the manifold wall is deformed inwardly towards the internal passage of the manifold. Figure 6(c) discloses an embodiment where no deformation of the manifold wall is carried out. All three embodiments are presented as alternatives, and there is no pointer to suggest to the skilled person that the embodiment of Figure 6(b) is particularly advantageous (or that it could address the technical problem at issue).

FORMULA/TABLE/GRAPHIC

In the absence of such a pointer, nothing can prima facie be identified that would motivate the skilled person to consult D5 and to adopt a particular solution of the prior art discussed in this document in order to combine it with D10 or D11. Thus, the objection is not prima facie relevant.

4.10.5 Combination of D10 or D11 with D6

The opponent argues that Figure 7 of D6 (reproduced below) discloses the distinguishing feature M1.9.

Figure 7 of D6 discloses a tapered portion of an opening (55; see column 6, lines 17 to 19). As in the case of D2 (see section 4.10.3 above), the relative dimensions of the material framing the opening and the diameter of the opening itself hint at an opening which is not produced by deformation of the manifold wall, contrary to feature M1.9.

FORMULA/TABLE/GRAPHIC

Moreover, the use of a jig (56) to deform the heat transfer tube (54) is incompatible with the microchannel construction of the heat transfer tubes of D10 (4) and D11 (12) since the work of the jig would collapse the end portions of the walls (D10: 4a; D11: 12a) defining the microchannels.

Consequently, combining either of D10 or D11 with D6 is not prima facie relevant.

4.10.6 Combination of D10 or D11 with D13

Document D13 discloses that the material of the manifold wall could frame its openings inwardly (Figures 1 and 4), outwardly (Figures 11 to 16) or that no framing material at all could be present around the openings (Figures 5, 6, 7, 17 and 18). No particular advantage of the embodiments of Figures 11 to 16 with regard to the posed technical problem is disclosed in D13 at first sight. Thus, the same logic as in section 4.10.4 applies here.

Furthermore, the system of D13 is based on flat tubes (2) having circular portions (2*) at their ends for connection with the manifold. The presence of parallel channels as in D10 (4a) and D11 (12a) is incompatible with this construction, since the exit of a large part of the lateral channels would be blocked due to the smaller diameter of the circular portion (2*) with respect to the total width of the flat tube (2) (see top view of Figures 2 and 3 as well as Figure 16 with regard to the side views of Figures 1 and 15).

In view of the above, the objection is not prima facie relevant.

4.11 As a result of the above, the aforementioned inventive step objections are not admitted into the proceedings pursuant to Article 13(2) RPBA 2020.

5. Main request - remittal request - Article 111 EPC

5.1 The opponent requested remittal of the case to the Opposition Division in case its inventive step objections were not admitted into the appeal proceedings under Article 13(2) RPBA 2020.

5.2 It would be contradictory to first not admit objections into the appeal proceedings only to then remit the case to the Opposition Division to allow a discussion of the very same objections in the opposition proceedings. The Opposition Division's second decision would then likely be based, within the meaning of Article 12(2) RPBA 2020, on these objections and the Board would then have to deal with them in substance in a second appeal, even though it did not admit them into the proceedings in the first appeal. Hence, not admitting certain objections into the appeal proceedings clearly does not constitute a special reason under Article 11 RPBA 2020 for remitting the case to the Opposition Division. The opponent's request to that effect is thus rejected in accordance with Article 111(1) EPC.