Andreas Stihl AG & Co. KG

Patent Trials and Appeals Board

Jul 27, 2021

2020006287 (P.T.A.B. Jul. 27, 2021)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
15/261,374 09/09/2016 Jan-Philipp Banzhaf A 95581 2605
47988 7590 07/27/2021
WALTER OTTESEN, P.A.
PO BOX 4026
GAITHERSBURG, MD 20885-4026
EXAMINER
CAMPBELL, JOSHUA A
ART UNIT PAPER NUMBER
3747
MAIL DATE DELIVERY MODE
07/27/2021 PAPER
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte JAN-PHILIPP BANZHAF and KARSTEN SCHMIDT
____________

Appeal 2020-006287
Application 15/261,374
Technology Center 3700
____________

Before CHARLES N. GREENHUT, GEORGE R. HOSKINS, and
MICHAEL L. WOODS, Administrative Patent Judges.

HOSKINS, Administrative Patent Judge.

DECISION ON APPEAL
Pursuant to 35 U.S.C. § 134(a), Appellant1 appeals from the
Examiner’s decision rejecting claims 1, 22, and 21 in this application under
35 U.S.C. § 103 as unpatentable over Dangelmaier (US 2013/0199812 A1,
published Aug. 8, 2013), Bahner (US 2009/0012699 A1, published Jan. 8,
2009), and Ostojic (US 2011/0000462 A1, published Jan. 6, 2011).
We REVERSE.

1 We use the word “Appellant” to refer to “applicant” as defined in
37 C.F.R. § 1.42. The Appeal Brief identifies Andreas Stihl AG & Co. KG,
and both of the named inventors, as the real parties in interest. Appeal Br. 2.
2 The Office Action on appeal is not clear regarding the status of claim 2. It
acknowledges claim 2 as a pending claim (Non-Final Act., dated Sept. 18,
2019, at 1), but does not thereafter address claim 2 (id. at 2–5). The Appeal
Brief does not address this uncertainty. See Appeal Br. 1, 4, 17. The
Answer adds claim 2 to the rejection, so we include it here. See Ans. 3–5.
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CLAIMED SUBJECT MATTER
Claims 1 and 21 are the independent claims on appeal. Claim 1
illustratively recites (see Appeal Br. 18–19 (Claims App.)):
l. A method for operating a work apparatus having
a combustion engine including a combustion chamber, a piston
delimiting the combustion chamber, a spark plug, an ignition
device configured to trigger an ignition spark at the spark plug
so as to ignite a fuel/air mixture in the combustion chamber, the
ignition device being configured to trigger an ignition spark at
the spark plug at an ignition time point (ZZP) in dependence
upon the rotational position of the piston, a work tool,
a crankshaft configured to drive the work tool, a centrifugal
clutch arranged between the crankshaft and the work tool, the
method comprising the steps of:
monitoring the rotational speed (n) of the combustion
engine;
advancing the ignition time point (ZZP) when the
following sequentially occurring conditions are satisfied:
i. a rich fuel/air mixture is supplied to the
combustion chamber,
ii. the rotational speed (n) lies in a
predetermined rotational speed range (nmin; nmax) within a
predetermined time period (ΔT), wherein the
predetermined rotational speed range (nmin; nmax) is
between 3,000 l/min and 5,000 l/min[3], and,
iii. the rotational speed (n) of the combustion
engine drops off to below a rotational speed limit value
(nG) after the conditions (i) and (ii) are satisfied,
so that, after the conditions (i), (ii) and (iii) are fulfilled,
a stopping of the combustion engine is prevented as a result of
the advancing of the ignition time point (ZZP).

3 The Examiner notes “[t]he units of ‘l/min’ appears to be a typographical
error because liters per minute is a measure of volumetric flow rate instead
of rotational speed,” and interprets claim 1 to recite “the rotational speed
range is between 3,000 and 5,000 revolutions per minute.” Ans. 7 (citing
Spec. 8:10–15).
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Application 15/261,374

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OPINION
A. Claims 1 and 2
The Examiner finds Bahner discloses, as recited in claim 1, a method
comprising “monitoring the rotational speed (n) of [a] combustion engine,”
and “advancing the ignition time point (ZZP) when” a portion of the claimed
conditions (ii) and (iii) is satisfied. See Non-Final Act. 3–4; Ans. 3–4. In
particular, the Examiner finds Bahner discloses advancing the ignition time
point “when . . . ii. the rotational speed (n) lies in a predetermined rotational
speed range (nmin; nmax) within a predetermined time period (ΔT),” as
required by claim 1. Appeal Br. 18 (Claims App., claim 1, lines 13–23); see
Non-Final Act. 3–4 (citing Bahner, Fig. 4, ¶¶ 27, 32, 42); Ans. 4. The
Examiner does not rely on either Dangelmaier or Ostojic in relation to this
claim limitation. See Non-Final Act. 3–4; Ans. 3–5.
We conclude a preponderance of the evidence does not support the
Examiner’s finding that Bahner discloses advancing the ignition time point
when the foregoing portion of condition (ii) in claim 1 is satisfied, so we
cannot sustain the rejection on appeal. First, we summarize Bahner’s
disclosure. Then, we consider the Examiner’s findings.
1. Summary of Bahner
Figure 2 of Bahner4 is reproduced on the next page:

4 The Examiner also cites Figure 4 of Bahner, which illustrates a more
complicated version of Figure 2. See, e.g., Bahner ¶¶ 38–41. Figure 2 is
representative of both Figures as to condition (ii) of claim 1, so we focus on
Figure 2 to simplify our discussion.
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Figure 2 “shows an ignition map that provides the ignition timing as a
function of engine speed.” Bahner ¶ 20. Accordingly, the horizontal axis
represents the engine’s rotational speed “n,” and the vertical axis “provides
the ignition timing IT as a function of the engine speed.” Id. ¶ 30. The
vertical axis origin corresponds to “ignition timing IT at the top dead center
of the piston,” so “[v]alues that are higher and farther up on the [vertical]
axis . . . indicate an advancement of the ignition timing IT (to earlier
timing).” Id. ¶ 30 (emphases added). Thus, where Appellant’s claim 1
recites “advancing the ignition time point” (Appeal Br. 18 (Claims App.,
claim 1, line 13)), this corresponds to moving higher along the vertical axis
in Bahner’s Figure 2 to earlier timing.
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Bahner provides two different ignition timing lines in Figure 2 for
correlating engine speed n to ignition timing IT. A first characteristic
line 24 is used during a “starting operation” of the engine, for engine speeds
between nStart,min and nStart,max. Bahner ¶¶ 31–32. A second characteristic
line 25, including descending branch 26, is thereafter used during “normal
operation” of the engine, for all engine speeds. Id. In other words, for
engine speeds between nStart,min and nStart,max, “each engine speed n has two
ignition timings correlated therewith, i.e. a first ignition timing on the
characteristic line 24 for the starting operation and a second ignition timing
on the characteristic line 25 [including branch 26] for normal (regular)
operation.” Id. ¶ 31.
Switching between the first and second characteristic lines “can be
realized based on one of several switching conditions.” Id. ¶ 42. Bahner
discloses three such conditions, which may be used alone, or in any
combination. Id. These conditions are: (1) “completion of a predetermined
number of engine cycles”; (2) “the engine speed n must have surpassed the
switching engine speed nswitch illustrated in FIG. 2”; and (3) “a
predetermined number of combustions has taken place.” Id.
2. The Examiner’s Findings Comparing Bahner with Claim 1
The Examiner finds Bahner discloses the “predetermined rotational
speed range (nmin; nmax)” of condition (ii) in claim 1 because Bahner’s
Figure 2 illustrates a “speed range . . . where the speed is above the Nswitch
threshold.” Non-Final Act. 3; Ans. 4. The Examiner further finds Bahner
discloses that the engine’s speed lies in that speed range “within a
predetermined time period (ΔT)” as claimed, because “[t]his must occur for
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a predetermined period of time/combustion cycles.” Non-Final Act. 3
(citing Bahner ¶ 42); Ans. 4.
Appellant asserts “The engine speed nswitch set forth in paragraph
[0042] of Bahner . . . is the basis of a completely different operating
principle” than the method of claim 1, so the Examiner errs in finding
“the same switchover conditions are present in Bahner” and in claim 1.
Appeal Br. 12.
Upon review of the foregoing, we discern two difficulties with the
Examiner’s reliance on Bahner in relation to condition (ii) of claim 1. First,
the claim requires a “predetermined rotational speed range (nmin; nmax)”
(emphasis added) — that is, a range with a minimum value (nmin) and a
maximum value (nmax). See also Spec. 8:5–17 (“[I]t is monitored in a first
element 50 [of Appellant’s Figure 4] whether the rotational speed (n) is
within a rotational speed range which is determined by the minimum
rotational speed nmin and the maximum rotational speed nmax.”). The
Examiner’s findings point to nswitch in Bahner as the minimum value of the
range, but do not point to any corresponding maximum value. As described
in Bahner, nswitch corresponds to a minimum engine speed for the ignition
time point control to switch from first characteristic line 24 to second
characteristic line 25 (including branch 26). Bahner ¶ 42. The Bahner
disclosures cited by the Examiner do not identify any maximum value of a
range that might correspond to nswitch as a minimum value. See Bahner
¶¶ 27, 32, 42. Bahner does discuss how nStart,min and nStart,max are the
minimum and maximum values of an engine speed range where first
characteristic line 24 may be applied to set the ignition time point (id. ¶¶ 31–
32), but we find no disclosure of nStart,max being used as the maximum value
of a range with nswitch being the minimum value.
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Second, the Bahner disclosures cited by the Examiner do not reflect
advancing the ignition time point when the engine speed remains above
nswitch “within a predetermined time period (ΔT),” as recited in condition (ii)
of claim 1. See Bahner ¶¶ 27, 32, 42. The Examiner here relies especially
on paragraph 42 of Bahner. Non-Final Act. 3 (citing Bahner ¶ 42). But,
paragraph 42 refers to “the engine speed n [surpassing] the switching engine
speed nswitch” as a different switching condition than “completion of a
predetermined number of engine cycles” and “a predetermined number of
combustions [taking] place.” Bahner ¶ 42. We find no disclosure of the
engine speed n needing to surpass nswitch for any particular amount of time,
whether measured in conventional units of time such as seconds, or other
units of time such as a number of engine cycles or combustions. Id. In
particular, there is no suggestion in Bahner that the counting of engine
cycles or combustions begins when the engine speed n surpasses nswitch, such
that Bahner might determine the engine speed n lies in a predetermined
range with a minimum value of nswitch for a predetermined time period. Id.
For the foregoing reasons, we do not sustain the rejection of claim 1
and its dependent claim 2 as having been obvious over Dangelmaier,
Bahner, and Ostojic.
3. Claim 21
Claim 21 like claim 1 recites “advancing the ignition time point (ZZP
when . . . ii. the rotational speed (n) lies in a predetermined rotational speed
range (nmin; nmax) within a predetermined time period (ΔT).” Appeal Br.
19–20 (Claims App.). The Examiner relies on Bahner as disclosing this
subject matter in claim 21. See Non-Final Act. 4 (“With regards to claim 21,
the claim is commensurate in scope with claim[] 1 and is rejected for the
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same reasons as set forth above.”); Ans. 5 (same). Thus, for the reasons
provided above, we do not sustain the rejection of claim 21 as having been
obvious over Dangelmaier, Bahner, and Ostojic.
SUMMARY OF DECISION
In summary, we reverse the Examiner’s rejection as to all claims 1, 2,
and 21, as set forth in this table:
Claims
Rejected
35 U.S.C. § References Affirmed Reversed
1, 2, 21 103 Dangelmaier,
Bahner, Ostojic
1, 2, 21
REVERSED