When trying to establish the existence of an inventive step, attorneys sometimes argue that the skilled person would not have done this or that because there was a well-known path he would rather have chosen when trying to solve the problem under consideration. Depending on the concrete circumstances, there may be some truth to this, but the present decision shows that the argument will not always work.
If you hate mechanics, you better not read on.
The applicant filed an appeal against the decision of the Examining Division to refuse his application.
Claim 1 of the main request before the Board read (in English translation):
Power tool (1) having a drive motor (2) and a flange (3) connected to it so that it can be driven, wherein a disk (5), in particular a grinding disk (Frässcheibe) or a separating disk (Trennscheibe), which can be attached so that it is hindered from rotating (drehfest anbringbar) and to which at least one transmission body (11) projecting from the flange (3) is moulded, characterised in that the outer contour of the transmission body (11) has an oval or ellipsoid shape and, when the disk (5) is mounted on the flange (3), [said outer contour] is curved in the direction of the circumference of the disk, in that the transmission body (11) is inclined with respect to the direction of the circumference of the disk (5), in that the disk (5) comprises at least one recess (12) having an oval or ellipsoid shape, wherein the recess is inclined towards the direction of rotation (8) of the disk (5) and curved and has an inner contour that matches the outer contour of the transmission body (11), in that the position of the transmission body (11) matches the corresponding position of the recess (12), in that, when the disk (5) is mounted, the transmission body (11) of the flange (3) is supported in a tight-fit fashion (formschlüssig) by the inner contour of the recess (12) of the disk (5), in that the disk (5) comprises a through bore (9) that is tapered conically towards the drive motor and into which a bolt (7) can be inserted, and in that the bolt (7) can be screwed into a threaded hole (6) provided in the flange (3), such that the head of the bolt (7) is positioned in the conically tapered through bore (9) of the disk (5) and the free ends of the transmission bodies (11) and of the bolt (7) extend through the planes defined by the disk (5).
The Board found claim 1 to differ from prior art document D4 by five distinguishing features:
(a) the outer contour of the transmission body has an oval or ellipsoid shape;
(b) when the disk is mounted on the flange, the outer contour is curved in the direction of the circumference of the disk;
(c) the transmission body is inclined with respect to the direction of the circumference of the disk;
(d) the disk comprises at least one recess having an oval or ellipsoid shape that is inclined towards the direction of rotation of the disk and curved; and
(e) the bolt can be screwed into a threaded hole provided in the flange.
The following paragraphs are taken from the Board’s discussion of the inventive step of this claim.
*** Translation of the German original ***
Effect of the distinguishing features
[4.3.1] According to the understanding of the appellant, which the Board considers to be correct and supported by the description of the application under consideration, the features (a) to (d) have the effect that the disk can be positioned precisely on the flange […].
As far as the at least one transmission body of the flange is concerned, the features (a) and (b) define its shape (in a sectional plane) and feature (c) defines its arrangement.
Feature (d) defines the corresponding [properties] of the at least one recess of the disk.
As regards the understanding of features (a) to (c) the Board – in favour of the appellant – bases its reasoning on the understanding that the outer contour of the transmission body at first has the basic shape of an oval or an ellipse (feature (a)) and that it is subsequently shaped in such a way that the transmission body is (over at least part of its length) curved in the direction of the circumference (feature (b)) and that the transmission body is arranged in such a way that it is inclined with respect to the direction of the circumference (feature (c)).
The same holds true for the shape and the arrangement of the recess in the disk.
As a consequence of this shape and arrangement of the at least one transmission body and the corresponding recess an interaction between the transmission body (or several transmission bodies) and the corresponding recess(es) is possible only if the disk is fit to the flange when the correct side of the disk faces the flange.
[4.3.2] Distinguishing feature (e) corresponds to an embodiment that differs – from a constructive point of view – from a power tool according to D4 by the way in which the bolt is screwed into the tool. Feature (e) was not discussed during the oral proceedings. It does not have any influence on the effect of the distinguishing features (a) to (d) and, when combined with the other features of claim 1, apparently does not give rise to any effect that has to be taken into account when inventive step is assessed.
The problem
[4.4] Considering the power tool according to the closest prior art D4 and taking into account the above mentioned effect of the distinguishing features (a) to (d), the problem to be solved corresponds to the first partial problem […], i.e. to adapt the known power tool such that the disk can be positioned precisely on a predetermined position of the flange.
The first partial problem is solved by a power tool having an appropriate shape of the flange, comprising at least one transmission body and the corresponding shape of the disk, comprising at least one recess, according to claim 1.
Obviousness
[4.5] When, depending on the way and the application in which the power tool according to D4 is used, [the skilled person] is confronted with the problem of positioning a disk precisely on a predetermined position of the flange, or in other words, of avoiding that the disk can be positioned on the flange in a position that is different from the precisely predetermined position, then it would be obvious to solve the first partial problem by arranging the known elements by which the disk is positioned on the flange, i.e. the pins, which have a circular cross-section and which are arranged symmetrically with respect to the centre of the flange, as well as the corresponding recesses, in an asymmetrical manner, so that the disk can be fit to the flange only from one particular side.
[4.5.1] In this context the Board agrees with the opinion of the appellant according to which there was a simple way of solving the partial problem in a way that differed from claim 1 and which allowed to keep the circular cross-section. If, as in D4 (Fig. 1), there were two pins, it was sufficient to asymmetrically arrange the two pins of the flange and the two recesses on the corresponding disk rather than having a symmetrical arrangement (in the circumferential direction) as in D4.
[4.5.2] However, the Board cannot endorse the further argumentation of the appellant, according to which, considering said obvious solution to the first partial problem, the different solution according to claim 1 cannot be considered to be obvious.
The Board is of the opinion that the present circumstance that, when starting from the power tool according to D4, there is another, obvious solution, which is different from the solution according to claim 1, cannot as such automatically lead to the conclusion that a further solution, such as the one of claim 1, is to be held non obvious.
[4.5.3] In the Board’s view, as far as the solution to the first partial problem according to claim 1 is concerned, and irrespective of any further obvious solutions, it rather has to be examined to which extent the solution according to claim 1 as such can be considered to involve an inventive step when starting from the closest prior art D4 and taking into account the remaining prior art, here D1/D2.
Prior art document D1/D2 discloses a power tool comprising a disk that can be fitted onto a flange, which is comparable in view of the allocation of a disk to a flange, and, therefore, in view of the first partial problem to be solved (cf. […] D1, figures 2 and 6).
When starting from the power tool according to D4, the skilled person would consider document D1/D2 because this document also aims at solving a problem that corresponds to the first partial problem. According to D1/D2, each transmission body and, accordingly, each recess that is associated with it, is arranged asymmetrically on the flange […]. According to an embodiment of D1/D2, one transmission body has a triangular shape and another has a U-shape, and the recesses in the disk have a corresponding shape […]. The transmission body and the recess, therefore, lead to an asymmetric configuration only because of their shape and arrangement – there is no need for an inclined arrangement of the triangular transmission body and the recess according to feature (c) […]. The effect is that the disk can be fit to the flange only from one particular side.
The Board is of the opinion that, starting from the power tool according to D4 and considering the way in which D1/D2 has solved the first partial problem, it is to be considered obvious to arrange the transmission bodies having a circular cross section according to D4, in an asymmetrical manner, by changing their cross sectional shape, taking into account the approach according to D1/D2.
It also has to be taken into account – as explained by the Board during the oral proceedings – that the features (a) to (c) of claim 1 concerning the shape and arrangement of the transmission body contribute to the solution to the first partial problem only to the extent that they lead to an asymmetrical arrangement of the transmission body on the flange. The same holds true for the disk, in view of feature (d). The shape or the arrangement of the transmission body (or the recess, respectively) does not contribute to the solution of the first partial problem beyond that point.
In this regard, the shape and the arrangement of the transmission body (and, in analogous manner, of the recess), such as, for instance, a kidney-shaped design, which features (a), (b) and (d) aim at, according to the appellant, are irrelevant and, therefore, arbitrary, if only the asymmetrical arrangement is maintained.
[4.5.4] As a consequence, the features (a), (b) and (d), which are directed to specific – not necessarily asymmetric – cross sectional shapes of the transmission body and the recess, cannot, neither alone nor in combination with the remaining features of claim 1, lead to subject-matter that involves an inventive step, because, as already explained, the cross-sectional shapes defined by those features cannot be ascribed any further effect beyond their asymmetrical arrangement according to feature (c) in view of the first partial problem to be solved.
[4.5.5] For the sake of completeness, it has to be noted in this context that, starting from the circular cross section of the transmission bodies according to D4, and taking into account the triangular cross section according to D1/D2, the transformation of the known spherical cross section into an oval one appears to be obvious.
As a consequence, the whole power tool according to claim 1 does not involve an inventive step within the meaning of A 56 over the closest prior art D4 of the further prior art according to D1/D2 is taken into account for solving the first partial problem.
[4.6] The above result also holds true if the further arguments of the appellant are taken into account.
[4.6.1] The further main argument of the appellant is based on a further effect of the features (a) and (d) within the combination of features of claim 1, which goes beyond the solution of the first partial problem and solves the second partial problem concerning the connection for operating the drive (triebliche Wirkverbindung) […]. According to this second problem of the present application […] an appropriate (gattungsgemäß) power tool is to be developed in such a way that the connection for operating the drive is both reliable and permanently available.
[4.6.2] The appellant is of the opinion that this problem is solved because, as explained in the description […] the transmission bodies fit without clearance to the recesses where the force is transmitted, which results in the torque of the flange being optimally transmitted without there being any abrupt stresses or peak values of shear forces resulting therefrom.
Moreover, as also stated in the description […] the available surface on which the torques act, is considerably increased by the inclined arrangement of the transmission bodies and recesses according to features (b), (c) and (d).
[4.6.3] Neither D4 nor D1/D2 contained any suggestion to shape and arrange the at least one transmission body and the corresponding recess according to features (a) to (d) in such a way that the power transmission via the at least one transmission body and the corresponding recess was also improved in view of solving the second partial problem. Document D4 only disclosed in this respect that two shear pins extending through corresponding through holes in the grinding disk were provided for the power transmission […]. As explained in the present application, the diameter of each recess was to be greater than the diameter of the corresponding pin in order to correct any manufacturing inaccuracies. In particular when the power tool was switched on and off, there would be strokes because the clearances resulting therefrom had to be overcome, and these strokes would lead to increased shear forces […] and could result in increased wear
[4.6.4] Moreover, the shape and arrangement of the at least one transmission body and the corresponding recess according to features (a) to (d) would greatly increase the available surface on which the torques could act […] so that the surface pressure between the transmission body and the recess was advantageously reduced.
[4.6.5] As regards the interaction between the transmission bodies and the recesses, D1/D2 only taught that the disk could be positioned precisely on a predetermined position of the flange thanks to an appropriate design and arrangement of these elements. According to this document, a further flange was provided between the flange and the disk for the power transmission (see figure 1 of D2 […]; there was no statement in D1/D2 on any interaction between the transmission body and the recesses in view of the power transmission.
[4.6.6] As a consequence, a combination of documents D4 and D1/D2 would not have led to the design and arrangement of the at least one transmission body and the corresponding recess according to features (a) to (d) in view of improving the co-operation of these elements to the transmission of power from the driven flange to the disk.
[4.7] Regarding this line of argument directed at the solution of a second partial problem, the Board is of the opinion that, as far as the assessment of inventive step is concerned, it may remain unanswered to which extent the power tool according to claim 1 may be considered obvious over the present prior art as solution to the second problem, when, as explained above […] the whole claimed power tool does not involve an inventive step as solution to the first problem over the present prior art.
[4.7.1] Moreover, the Board is of the opinion that, taking into account the corresponding arguments of the appellant, the power tool of claim 1 is to be considered obvious with respect to documents D4 and D1/D2 even if, as argued by the appellant, the second partial problem is taken into account.
First of all, as regards the power tool defined in claim 1, it is questionable to which extent the mentioned effects (absence of clearance, increased surface for power transmission) can be derived from the combination of claim 1 with the features (a) to (d). As far as the allocation of the transmission bodies to the recesses without any clearance is concerned, claim 1 – as explained by the Board during the oral proceedings – does not contain any explicit indication. The same holds true for the greatly increased surface that is said to be available for the transmission of power, because claim 1 does not contain any definition regarding the dimension of the cross sectional areas of the transmission bodies and the recesses, respectively, nor does it define the extent of the inclined positioning of those elements.
[4.7.2] But even if it is considered, in favour of the appellant, that these effects are indeed obtained as a consequence of the combination of features of claim 1, the line of arguments based thereon is not persuasive.
The Board is of the opinion that it may indeed remain unanswered to which extent document D1/D2 teaches that, as contested by the appellant, the transmission bodies and recesses of the embodiment according to figures 6(a) and 6(b) (in connection with figure 2) of D1 contribute to the power transmission from the driven flange to the disk.
[4.7.3] As a matter of fact, in view of the contribution of the at least one transmission body and the corresponding recess, it has to be taken into account that in the power tool according to D4, these elements already co-operate in the way in which they were said to co-operate in the argumentation of the appellant in view of the power tool according to claim 1. In this respect, D4 explains that “for the transmission of power, two shear pins are provided on the driving shaft 5 and extend through corresponding through holes in the grinding disk 4” […].
One has to consider that the skilled person, when designing the transmission bodies and the recesses asymmetrically, according to D4 taking into account the approach according to D1/D2 […], would not modify the power transmission via those elements, not only because of the explicit reference to this way of transmitting power in D4, but only because in the power tool according to D4, according to the approach of claim 1 […] the disk is held on its side that is opposite to the drive motor only by means of a fixing screw (see D4, figure 1). Therefore, a power tool according to the closest prior art, similar to a power tool according to the present application (figure 1) and contrary to the one of D1/D2 (cf. figure 2) does not have a second flange which could also serve for power transmission.
[4.7.4] For the sake of completeness, it should be noted that the skilled person further developing the closest prior art in order to solve a technical problem, here the first partial problem, has no reason to carry out modifications that do not contribute to the solution of the problem, in the present case by modifying the shape of the at least one transmission body and the corresponding recess. This is particularly true when, as in the present case, the modification would considerably change the construction of the power tool because it would modify the constructive elements serving the power transmission.
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