T 1530/09 – The Whole Truth

Although it is in principle possible to amend claims based on figures, such an amendment will not be possible if the teaching of the application as filed as a whole does not provide any support for the amendment, as the present decision shows.

In this case, both the opponent and the patent proprietor filed an appeal against the decision of the Opposition Division (OD) to maintain the patent in amended form.

Claim 1 of the main request before the Board was identical to claim 1 as granted :

An emission control apparatus of an internal combustion engine (10) having a storage device (22) provided in an exhaust passage (18) of the internal combustion engine (10) that stores a threshold level of NOx, and control means (40) that reduce NOx stored in the storage device (22) to recover a NOx storing level of the storage device (22) by performing a rich spike control by temporarily shifting during a lean burn operation of the internal combustion engine (10) an engine air-fuel ratio to a fuel-rich ratio,

wherein the control means (40) limit an execution time of the rich spike control, and perform a stoichiometric burn operation in which the engine air-fuel ratio is stoichiometric, after the execution time limited by the control means (40) elapses,

wherein the control means (40) switch to the stoichiometric burn operation when the limited execution time of the rich spike control elapses without recovering the NOx storing level and switch from the rich spike control to the lean burn operation when the NOx storing level is recovered,

wherein the control means switch from the rich spike control to the lean burn operation when the limited execution time of the rich spike control set by the control means (40) is not achieved but the NOx storing level is recovered.

The opponent pointed out that the subject-matter of claim 1 as granted was not disclosed in the application as originally filed : the entire application as filed made no reference to a direct switch from rich burn to lean burn, but only to the prevention of deterioration of CH and CO emissions (itself caused by prolonged rich spike control) by using a stoichiometric burn operation between rich and lean burn modes. Such operation should not be understood as omitted by the flowchart of Figure 2. Although the flowchart included a logic pathway seemingly indicating a possible omission of stoichiometric burn, this would not be considered correct by the skilled person as it would not be consistent with the timing chart of Figure 3 which highlighted the step of stoichiometric burn as the distinguishing feature with respect to the prior art process shown in Figure 4.

The patent proprietor relied on the flowchart of figure 2.

What did the Board decide ?

[1.1] Claim 1 includes a combination of the features of originally filed claims 1, 2 and 7, whereby claim 7 as filed however did not depend on claim 1 but only on independent claim 5. Furthermore, the following feature has been added to the wording of claim 1:

“wherein the control means switch from the rich spike control to the lean burn operation when the limited execution time of the rich spike control set by the control means (40) is not achieved but the NOx storing level is recovered.”

[1.2] Hence, the subject-matter of claim 1 is directed to the embodiment disclosed in the patent in suit which concerns a control apparatus arranged to perform the sub-sequence of the steps: lean burn - rich burn - stoichiometric burn - lean burn, but wherein the control apparatus is arranged also to include an alternative of omitting stoichiometric burn under certain conditions. Claim 1 as originally filed however required the control means to be arranged to perform a stoichiometric burn operation between the rich burn and the lean burn.

[1.3] Figure 2, which was cited by the appellant (proprietor) as disclosing both options, is a flowchart illustrating a processing procedure of the NOx storing capability recovering process.

It is correct that this flowchart includes the logic pathway of omitting the step of stoichiometric burn. Such option depends on whether the time duration set for the rich spike burn has elapsed or not (S270). The option of switching directly from rich burn (S260) to lean burn (S310) concerns the case where the rich spike duration is shorter than the set value (i.e. S270 “NO”) and additionally where the NOx has been recovered (i.e. S290 “YES”), in which case step S300 follows and sets the XRICHS flag to the OFF position, whereupon the procedure continues with a switch to lean burn (S310) and then ends the program.

[1.4] Hence, the question of whether the skilled person would consider the omission of the stoichiometric burn as an option which was disclosed in the application as filed has to be assessed on the basis of the whole contents of the specification and thus taking into account the disclosure in the description.

[1.5] The description of the patent in suit highlights as the basic issue […] the control of HC and CO emissions effectively by avoiding prolonged rich spike control and thus switching from the rich spike control to a stoichiometric burn operation. The underlying concept therefore includes the complete recovery of the NOx storing level of the storage device during stoichiometric burn operation to thereby curb deterioration of NOx emissions while at the same time avoiding deterioration of HC and CO emissions even when the amount of exhaust gas becomes great. It is consistently disclosed […] to set the duration time for the rich burn to be sufficiently short so as to obtain recovery of the NOx storing level during the stoichiometric burn operation.

Such consistent timing chart is complementarily shown in Figure 3 which shows that it is precisely the presence of a stoichiometric burn period directly subsequent to the rich burn duration which distinguishes the process and control means of the patent in suit from the process of the related art shown in Figure 4.

Thus for a skilled person, the flowchart of Figure 2 has to be read in line with this underlying concept of the process steps and not in isolation.

[1.6] In this regard it is undisputed between the parties, that there is no disclosure whatsoever in the description that the step of stoichiometric burn should or could be omitted. According to the general references in the description, there is no doubt about the skilled person being aware of the various interactions in the emission procedure (e.g. type of combustion engine, materials, temperatures, velocities) and being capable of correctly calculating and determining a time interval for the duration of rich burn. This duration period has to be calculated on the basis of the amount of the stored NOx, and has to be set sufficiently short in order to curb HC and CO-emissions via a subsequent stoichiometric burn operation even though no details of such calculation or determination are disclosed. However the skilled person is well-trained and has experience in such field such that setting a suitable time period to achieve this would be well within his knowledge.

[1.7] Concerning the logic pathway possibility shown in the flowchart of Figure 2 of seemingly omitting the switch to the stoichiometric burn by directly changing from a rich spike to lean burn, the purpose of that pathway is however unambiguously evident from the description (see paragraph [0035] of the A-publication, which states: “At this moment, the rich spike control has just started, and the rich spike duration Tr is less than the set value. Therefore, the unit 40 proceeds to step S290, in which the unit 40 determines whether the amount of NOx stored has become “0”.”). Thus, that pathway is intended to be used only for the time at the beginning of the rich spike duration when the rich spike duration is less than the set value and hence, directly after switching to rich burn. At such time neither the rich spike duration Tr can have elapsed nor the amount of stored NOx can be zero and the procedure must, evidently, remain in the rich burn (sub-sequence of steps S270 “NO”, S290 “NO”, “END”, return to S220, and rich burn is continued (paragraph [0036] of the A-publication). Hence, this sequence of steps is entirely in line with the general concept given in the description of the application as filed.

[1.8] There are no conditions disclosed in the patent in suit (concerning the determination and setting of the duration time of the rich burn or the amount of stored NOx) which would even suggest to a skilled person another possibility or other purpose of the steps disclosed in the flowchart than the one described which includes a step of stoichiometric burn.

[1.9] Thus, although there is a logic possibility within the flowchart of Figure 2 not to enter the step of stoichiometric burn, the description of the patent in suit discloses clearly and unambiguously to the skilled person that the value for the duration of the rich burn must be set correctly, which means in the present case being sufficiently short in order to allow the step of stoichiometric burn to be entered. Although it might be the case that if the rich spike control duration were set to be sufficiently long, a direct switch from rich to lean burn might occur if the flowchart were considered in isolation, nothing in the application as filed discloses in an unambiguous manner that such a duration would be set. Indeed, avoidance of the stoichiometric burn operation (which is not disclosed) would in fact only be the result of an unintended and thus incorrect setting of the rich spike duration by a skilled person.

[1.10] Claim 1, however, defines a control means which is specifically arranged to include this alternative option disclosed in isolation only as a logic pathway in Figure 2, namely switching directly from the rich spike control to the lean burn operation without requiring a stoichiometric burn operation to be included. When considering the whole contents of the application as filed however, there is no unambiguous disclosure of the control means being arranged in such a manner that it could ever switch from rich to lean burn directly.

Although the proprietor argued that e.g. atmospheric conditions might exist under which the control system would switch directly from rich to lean burn, this is not disclosed anywhere in the application as filed. More importantly however, since the flowchart of Figure 2 is used together with the description to aid understanding thereof (notably also together with Figure 3), it may even be the case that other sub-routines not shown in the flowchart would account for any such conditions. Without any disclosure in the application as filed to indicate that a switch from rich burn to lean burn might indeed occur under a specific set of conditions, the proprietor’s argument is nothing more than mere speculation.

The subject-matter of claim 1 of the main request thus extends beyond the content of the application as originally filed (A 100(c)), whereby the main request is not allowable.

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