T 0471/16 03-09-2019

I. European patent No 2 452 022 (in the following: "the patent") concerns a cutter head for dredging ground under the water surface.

II. The patent as a whole was opposed on the grounds of insufficient disclosure (Article 100(b) EPC), lack of novelty and lack of inventive step (Article 100(a) EPC).

III. The opposition division held that the patent as amended on the basis of the main request before it met the requirements of the EPC.

IV. This intermediate decision was appealed by the opponent (in the following: the appellant).

V. With summons to oral proceedings, the Board sent a communication pursuant to Article 15(1) of the Rules of Procedure of the Boards of Appeal (RPBA) indicating its preliminary opinion of the case.

VI. Oral proceedings before the Board were held on 3 September 2019.

VII. Final requests

The appellant requested that the appealed decision be set aside and the patent be revoked.

The patent proprietor (in the following: the respondent) requested that the appeal be dismissed, alternatively that the decision under appeal be set aside and the patent be maintained in amended form on the basis of one of the sets of claims filed as first, second and third auxiliary requests with letter dated 3 June 2019.

VIII. Claims of the appellant's main request

Independent apparatus claim 1 as amended reads as follows (the feature numbering is introduced by the Board for ease of reference; compared with claim 1 as granted, added passages are indicated in bold, deleted passages in strike-through):

(a) Cutter head (10) for dredging ground under the

water surface, comprising

(b) a revolving body (11) which is rotatable around a

central axis and

(c) which is formed by a base ring (13) and a hub (14)

placed at a distance therefrom,

(d) between which extend a number of support arms (15)

provided with cutting tools (20),

(e) between which support arms (15) passage openings

(16) are present for discharge of the dredged

ground,

characterised in that

(f) the cutter head comprises at least [deleted: 50] 100 cutting

tools,

(g) which cutting tools (20) are axisymmetrical at

least at their free outer end.

IX. Cited evidence

(a) In the statement setting out the grounds of appeal, and in the reply to it, the parties referred among others to the following documents which were filed in the opposition proceedings and are cited in the decision under appeal:

D1: US 4,319,415 A;

D2: WO 2005/035884 A1;

D3: GB 2 032 492 A;

D8: DE 10 2005 051 450 B4;

N1: Product information on "bosta - Cutter systems for

soft and hard soils", Stapel shipyard, Spaarndam

(NL), 6 pages, with imprint "86-01";

N2: WO 2007/100250 A1;

N3: Roxborough, F.F. and Sen, G.C., "Breaking coal and

rock", chapter 9 of "Australian coal mining

practice", 1986, pages 30 to 147;

N4: NL 8000 840 A;

N5: US 4,736,533 A;

N9: Product information on "Dura-Point® Tooth"

from the journal "International dredging and port

construction", Vol. IV, No 6, April 1977, pages 1

and 12.

(b) With letter dated 1 September 2016, the appellant filed the following document:

N10: Expert opinion by Prof. C. van Rhee

In addition, the appellant offered the expert testimony of Prof. C. van Rhee.

(c) With letter dated 27 October 2016, the respondent filed the following document:

N12: Product information on "ESCO® Dredge Products-

Spherilok**(®) and Helilok**(®) Cutterheads", ESCO, 2003,

8 pages

(d) In addition, with letter dated 3 June 2019, the respondent filed the following document:

N13: Written statement by Mr. K.G. Wijma

X. The arguments of the parties, insofar as relevant for the present decision, can be summarised as follows:

(a) Admission of N10 and N13 in the appeal proceedings

The respondent requested the Board not to admit document N10 into the proceedings because it was filed at a late stage.

The appellant requested the Board not to admit document N13 into the proceedings because it was filed at a very late stage.

(b) Main request - Novelty

Appellant's case:

D3 discloses a cutter head including a base ring 14, a hub 23 and four pairs of helical webs 13 extending between them and carrying cutter bits 19. The opposition division erred in deciding that this head does not comprise features (d), (f) and (g) of claim 1.

Each web pair forms a support arm as required by feature (d). They fulfill the function of support arms because they support the cutter bits. The claim wording does not exclude that the support arms are as flange-like as webs 13. In practice there is no clear distinction between flangy and army type supports. As shown in figure 1 of D1, the support arms can be relatively flange-like.

With respect to feature (g) it is apparent in figures 1 to 3 of D3 that the cutter bits 19 are conical rock bits. This is confirmed by the teaching on page 1, lines 16 to 25 that the cutter head is adapted for dredging hard rock with an Unconfined Compressive Strength (UCS) of about 48 MPa.

With respect to feature (f) figures 1 to 3 clearly show that each pair of webs 13 has 26 cut-outs 16 for mounting cutter bits 19, making a total of 104 bits. In fact, according to an expert in the art (document N10), the cutter head is equipped with 120 bits.

Respondent's case:

D3 fails to disclose features (d), (f) and (g) for the reasons set out by the opposition division in the decision under appeal.

The term "support arm" in feature (d) must be construed to have its normal meaning in the art of dredging. It is generally known that, in a conventional rotatable cutter head for a cutter suction dredger, several arms (sometimes also referred as blades due their cutting function) protrude from a base ring to support a hub, whereby ground material cut loose passes through the openings between the support arms (see D1; D2; D3, column 1, lines 4 to 10; N1; N2; N12). The pairs of webs 13 disclosed in D3 do not anticipate such support arms.

With respect to feature (g), D3 is silent about the number of cutter bits. Since 17 cutter bits (reference numeral 19) are shown in figure 1, which is a side view of the head, there are probably only 34 bits in total (17 per side). Contrary to the appellant's assertion, it cannot be derived from D3 that bits 19 are positioned in all cut-outs 16. Even if they were, it cannot be derived from D3 that the cutter head would comprise at least 100 bits. Contrary to the appellant's view, figures 1 to 3 do not show that each web pair has 26 cut-outs. In fact, figure 3 shows a web pair with only 16 cut-outs. The expert alleges that 60 cut-outs are shown in figure 1 and that their total amount is 120 (N10). However, less than 50 cut-outs are shown in figure 1. Moreover, the cut-outs at the edge of the head in figure 1 are located either on the other non-visible side or at the exact middle plane, and hence they must be counted only once. Finally, there is no reason to assume that the number of cut-outs on the non-visible side is the same as on the visible side.

With respect to feature (g), it cannot be derived from D3 that the cutter bits 19 are conical teeth. In fact, the shape of the bits is not clear from D3.

(c) Main request - Inventive step

Appellant's case:

The subject-matter of claim 1 does not involve an inventive step in view of the following documents:

a) N2 alone or in combination with N1;

b) N1 ("Bosta SC") in combination with N9, N4 or D3;

c) N1 ("Bosta D") in combination with N9 or D3;

d) D3 alone or in combination with N1; or

e) D1 in combination with N3 and possibly N1.

Attack a):

N2 discloses a cutter head with cutting tools in the form of conical teeth for cutting hard ground (page 1, line 17 and page 2, line 25; figures 1 to 5, teeth 12), contrary to the opposition division's view. The cutter head comprises six support arms carrying 60 teeth in total. Thus, the cutter head defined in claim 1 differs from that disclosed in N2 only by feature (f). The technical problem objectively solved by this feature is how to increase efficiency when dredging hard ground (see paragraph 11 of the patent specification). The skilled person faced with this problem, and assisted by their common general knowledge, would inevitably increase the size of the head and/or reduce the size of the teeth, and thus use at least 100 teeth. This is confirmed by the opinion of an expert in the art of dredging (document N10). In addition, N1 suggests using so many teeth because it discloses a similar cutter head with six support arms carrying 120 teeth (see head "Bosta SC" on front page). The mere fact that this head is used for dredging clay or peat would not hinder the skilled person from providing the cutter head of N2 with 100 teeth or more.

Attack b):

The subject-matter of claim 1 differs from the cutter head "Bosta SC" disclosed in N1 by feature (g). As with N2, this distinguishing feature solves the objective problem of how to increase efficiency when dredging hard ground. The claimed solution to this problem is rendered obvious by N9 which discloses conical pencil-point picks for efficiently dredging hard rock. The mere fact that Bosta SC comprises cutting tools in the form of flared points would not hinder the skilled person from replacing these cutting tools with conical picks as shown in N9.

Attack c):

In addition to Bosta SC, N1 discloses a cutter head with 60 cutting tools for dredging rock with a UCS of up to 250 MPa (head "Bosta D"). The subject-matter of claim 1 differs from it by features (f) and (g). Since these distinguishing features do not interact to achieve a synergistic effect, they can be treated independently when assessing their obviousness. For the reasons set out above with regard to Bosta SC, the provision of feature (g) is rendered obvious by the teaching of N9. Alternatively, the skilled person would look for suggestions in the neighbouring field of trenching and N4 would motivate them to replace the flared points of Bosta D with conical points. For the reasons set out above with regard to N2, the provision of feature (f) is rendered obvious by common general knowledge and/or N1. In addition, features (f) and (g) are rendered obvious by the teaching of D3.

Attack d):

Should the Board decide that D3 fails to disclose features (d) and (f), these features could not lead to an inventive step. With respect to feature (d), the skilled person starting from D3 and looking to make the support structure for the cutting tools more robust, or simply to provide an alternative support structure, would consider replacing the pairs of webs 13 by support arms extending from the base ring to the hub, because this is the conventional support structure in the art, as documented in N1 or N12. Alternatively, if the skilled person were to beef up the webs 13, they would arrive at the flange-like arms in an obvious manner. With respect to feature (f), this modification would be obvious, for the reasons set out above with regard to N2. In fact, D3 dates from 1980 and the skilled person seeking to use the cutter head of D3 in a modern large-sized cutter suction dredger would inevitably scale up the head and thus use at least 100 cutter bits.

Attack e):

The cutter head defined in claim 1 differs from that disclosed in D1 only by features (f) and (g). For the skilled person looking to increase efficiency when dredging hard ground, the provision of conical teeth is rendered obvious by the teaching of N3 (feature (g)). Once the desired tooth spacing has been established, it is only a matter of size of the head and of the driving power to end up with at least 100 teeth (feature (f)). Alternatively, this latter feature is rendered obvious by N1, for the reasons set out above with regard to N2.

Respondent's case:

The claimed subject-matter involves an inventive step when starting from N2, N1, D3 or D1 as closest prior art.

Attack a):

In addition to feature (f), N2 fails to disclose feature (g). In the drawings of N2, items 12 are not teeth but adapters to which teeth may be removably fitted, as stated on page 6, line 33. Even if items 12 are considered to be teeth, it cannot be derived from N2 that they would be axisymmetrical at their free outer end (feature (g)). N2 is concerned with the provision of non-return means in the form of valves/flaps 13 to prevent spillage of cut ground material (page 3, lines 8 to 15), not with the provision of specific teeth for cutting ground material. Therefore a skilled reader would not attach any significance to the teeth shown in the drawings, in particular because the illustrations are highly schematic. In practice, the teeth were intended to be asymmetrical pick points, as explained by the inventor of N2 (see document N13).

The technical problem objectively solved by features (f) and (g) is that of how to provide a cutter head for a suction dredger that is more efficient in hard ground (see paragraphs 11 and 25 of the patent specification). The skilled person facing this problem would have no motivation to modify the shape and number of the cutting teeth in the claimed manner.

Contrary to what is stated in the expert opinion N10, this modification is not rendered obvious by common general knowledge before the priority date (6 July 2009). When dredging hard ground, it was conventional practice to strike large fragments out of the ground with great force, not to break off small pieces of ground, as with the invention. In view of the fact that teeth are prone to wear or damage, the skilled person seeking to increase dredging efficiency would tend not increase the number of teeth. Instead, they would replace the conical teeth of N2 by bigger asymmetrical teeth (see Bosta D in N1).

Whilst N1 teaches that a cutter head with 120 cutting teeth in the form of flared points prevents clogging when dredging clay ("Bosta SC"), this specific teaching is not compatible with that of N2. Clay is a soft pudding-like material which can be dredged with cutting tools in the form of flared points, acting like spoons shovelling the pudding. Pick points or conical pencil-point picks are only suitable for dredging much harder ground, such as rock. N1 also discloses the cutter head Bosta D having 60 cutting teeth in the form of asymmetrical pick points for efficiently dredging hard rock with a UCS of up to 250 MPa ("Bosta D"). This teaching is compatible with that of N2 and would lead the skilled person away from features (f) and (g).

Attack b):

The subject-matter of claim 1 differs from the cutter head Bosta SC disclosed in N1 by feature (g). For the skilled person seeking to increase efficiency when dredging hard ground, this distinguishing feature is not rendered obvious by N9, N4 or D3. Contrary to Bosta SC, which is used for dredging soft ground such as clay and peat, N9, N4 and D3 relate to heads for cutting much harder ground such as rock. Thus, the skilled person would not consider their teachings. Even if they were to consider any of these teachings, they would recognise that conical pencil-point picks as disclosed therein would not be adequate for dredging clay or peat. Thus, the skilled person would not replace the flared points of Bosta SC with conical picks, as this would run counter to the function of Bosta SC.

Attack c):

The subject-matter of claim 1 differs from the cutter head "Bosta D" by features (f) and (g). For the skilled person seeking to increase efficiency when dredging hard ground, none of these modifications would be obvious. In fact, the skilled person would rather use bigger and heavier asymmetrical teeth, as suggested by D2 (figure 8) and N12, rather than axisymmetrical ones. Even if they were to replace the asymmetrical pick points of Bosta D by conical teeth as disclosed in N9, they would not arrive at feature (f). This feature is not rendered obvious by common general knowledge, let alone N1, for the reasons set out above with respect to N2.

Attack d):

Should the Board decide that the subject-matter of claim 1 differs from D3 by features (d) and (f), the provision of these distinguishing features involves an inventive step. With regard to feature (d) the skilled person seeking to reinforce the structure supporting the cutting bits is not provided with a clear motivation to modify the pairs of webs in the claimed manner. Instead, using the common general knowledge in the art, they would rather consider improving the webs' stability by increasing the webs' thickness or arranging stiffeners on them. With regard to feature (f) the appellant's assertion that it results automatically from a scaling-up of the cutter head of D3 is mere speculation. Furthermore, the skilled person has no clear motivation to scale up this head.

Attack e):

D1 fails to disclose features (f) and (g). The objective problem is how to provide a cutter head for a suction dredger that is more efficient in hard ground. N3 documents general knowledge about breaking coal and rock in underground mining, as opposed to D1 which relates to dredging underwater. Therefore, when addressing the objective technical problem, the skilled person would not consider the teachings of N3. Even if they did, D1 and N3 would not motivate them to increase the number of cutting tools to at least 100.