Ex Parte Sun et al

Patent Trial and Appeal Board

Jul 23, 2018

14383750 (P.T.A.B. Jul. 23, 2018)

UNITED STA TES p A TENT AND TRADEMARK OFFICE
APPLICATION NO. FILING DATE
14/383,750 09/08/2014
26096 7590 07/25/2018
CARLSON, GASKEY & OLDS, P.C.
400 WEST MAPLE ROAD
SUITE 350
BIRMINGHAM, MI 48009
FIRST NAMED INVENTOR
Lin Sun
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
ATTORNEY DOCKET NO. CONFIRMATION NO.
67426-032 PUSl 7974
EXAMINER
TANENBAUM, TZVI SAMUEL
ART UNIT PAPER NUMBER
3744
NOTIFICATION DATE DELIVERY MODE
07/25/2018 ELECTRONIC
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.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
ptodocket@cgolaw.com
cgolaw@yahoo.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte LIN SUN and JOOST BRASZ 1
Appeal2017-009593
Application 14/383,750
Technology Center 3700
Before JOHN C. KERINS, JAMES P. CAL VE, and LISA M. GUIJT,
Administrative Patent Judges.
CAL VE, Administrative Patent Judge.
DECISION ON APPEAL
STATEMENT OF THE CASE
Appellants appeal under 35 U.S.C. § 134(a) from the Final Office
Action rejecting claims 1, 3, 6-9, and 12-15. We have jurisdiction under
35 U.S.C. § 6(b).
We AFFIRM.
1 Danfoss A/S is identified as the real party in interest. Appeal Br. 1.
Appeal2017-009593
Application 14/383,750
CLAIMED SUBJECT MATTER
Claims 1 and 9 are independent. Claim 1 is reproduced below.
1. A heat pump system comprising:
a refrigerant circuit;
first and second heat exchangers arranged in the
refrigerant circuit;
a flow reversing device selectively changing a direction
of flow in the refrigerant circuit between the first and second
heat exchangers; and
a centrifugal compressor arranged in the fluid circuit and
having first and second impellers arranged in series relative to
one another and providing a desired compressor pressure ratio,
wherein the first and second impellers respectively include first
and second stage inlets and outlets, and the desired compressor
pressure ratio corresponds to a second stage outlet pressure to a
first stage inlet pressure, wherein the compressor includes first
and second diffusers respectively arranged at the first and
second stage outlets, and wherein the first and second diffusers
are variable geometry diffusers, and the compressor includes
first and second actuators configured to respectively move the
first and second variable geometry diffusers between first and
second positions.
Appeal Br. 7 (Claims App'x).
REJECTIONS
Claims 1, 7, and 8 are rejected under 35 U.S.C. § I03(a) as
unpatentable over Conry (US 5,857,348, iss. Jan. 12, 1999), Shoemaker (US
4,739,628, iss. Apr. 26, 1988), and Nenstiel (US 6,872,050 B2, iss. Mar. 29,
2005).
Claim 3 is rejected under 35 U.S.C. § I03(a) as unpatentable over
Conry, Shoemaker, Nenstiel, and Tetu (US 2010/0263391 Al, pub. Oct. 21,
2010).
2
Appeal2017-009593
Application 14/383,750
Claim 6 is rejected under 35 U.S.C. § 103(a) as unpatentable over
Conry, Shoemaker, Nenstiel, and Merola (US 4,033,738, iss. July 5, 1977).
Claims 9, 12, 14, and 15 are rejected under 35 U.S.C. § 103(a) as
unpatentable over Conry, Nenstiel, and Tetu.
Claim 13 is rejected under 35 U.S.C. § 103(a) as unpatentable over
Conry, Nenstiel, Tetu, and Merola.
ANALYSIS
Claims 1, 7, and 8
Rejected Over Conry, Shoemaker, and Nenstiel
Appellants argue claims 1, 7, and 8 as a group. Appeal Br. 3-5. We
select claim 1 as representative, with claims 7 and 8 standing or falling with
claim 1. 37 C.F.R. § 4I.37(c)(l)(iv).
The Examiner finds that Conry teaches a heat pump system, as recited
in claim 1, including heat exchangers 43, 47 and centrifugal compressor with
first and second stage compressors 1 7, 18 and first and second impellers 19,
21 arranged in series to provide the desired pressure ratio. Final Act. 2. The
Examiner relies on Shoemaker to teach a flow reversing device 20 to change
flow direction selectively. Id. at 3. The Examiner relies on Nenstiel to teach
a variable geometric diffuser 110 for centrifugal compressor 100 at an outlet
flow path 134 as claimed. Id. at 4. The Examiner determines it would have
been obvious to modify Conry with Nenstiel's teaching to provide diffusers
at the outlets of the first and second stages of Conry's compressor to control
the amount of fluid that flows through each outlet and compressor stage, to
prevent surge conditions, and to maximize fluid flow by changing the area of
the first and second stage outlets as Nenstiel teaches. Id. at 5, 9; Ans. 2-5.
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Appeal2017-009593
Application 14/383,750
Appellants argue that there is no teaching in the prior art of record to
use two variable geometry diffusers, and it would not have been obvious to
extrapolate a second diffuser from a reference that only teaches one diffuser.
Appeal Br. 3--4. Appellants argue that adding a second diffuser downstream
of a second impeller is not a mere duplication of parts as the Examiner has
determined. Id. Appellants further argue that the Examiner's reason for
providing a second diffuser downstream of the second impeller "to control
flow through two compressor stages, and thereby more completely control
the flow of fluid through the compressor" is not supported by any prior art
reference and instead relies solely on hindsight. Id. at 4. Appellants assert
that the claimed combination provides an increased pressure ratio that has
criticality. Id. at 4--5. Finally, Appellants argue that Conry does not require
variable geometry diffusers because Conry includes inlet guide vanes so the
removal of inlet guide vanes changes the principle of operation. Id. at 5.
These arguments are not persuasive for the following reasons. First,
the Examiner's reason for adding a diffuser to the outlet of each impeller and
stage of Conry' s two-stage centrifugal compressor is supported by a rational
underpinning based on Nenstiel's teachings of the benefits of using diffusers
at stage outlets of centrifugal compressors. In this regard, Nenstiel teaches
that "many compressor designs include a diffuser positioned at the impeller
exit to stabilize the fluid flow." Nenstiel, 1: 18-20. Nenstiel further teaches
that the diffusers are used in such designs to decrease the area at the impeller
exit and thereby stabilize flow to prevent fluid stall and surge conditions. Id.
at 1:40-55, 5:52---63; see Final Act. 5 (it would have been obvious to include
diffusers at the first and second stage outlets of Conry to control the amount
fluid flowing through the outlets and to prevent a surge condition).
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Appeal2017-009593
Application 14/383,750
Appellants argue that N enstiel' s teachings of the benefits of using a
diffuser at an impeller outlet of a centrifugal compressor is not applicable to
impeller outlets of a multi-stage centrifugal compressor as claimed. Reply
Br. 1 ("Nenstiel only fairly teaches providing a diffuser after a first stage,
not to both of Conry's stages."); see Appeal Br. 4 (arguing that "the addition
of a second diffuser downstream of the second impeller is not the same as
merely 'duplicating' a rib configured for sealing" and further arguing that
"one would not merely 'extrapolate' a second diffuser from a reference that
only teaches one diffuser, contrary to what the Examiner alleges.").
This argument is not persuasive in view of the teachings ofNenstiel,
which we do not consider to be as limited as Appellants assert. In particular,
Nenstiel teaches to use a diffuser at the outlet of an impeller of a centrifugal
compressor to manage transitions undergone by a compressor based on load
increases and decreases of a refrigeration circuit. As the flow of refrigerant
changes during operation of a compressor due to changing loads, the diffuser
extends and retracts to adjust the area at the impeller exit for different fluid
flow rates thereby stabilizing ( controlling) fluid flow and preventing adverse
stall and surge conditions. Nenstiel, 1: 11-55, 5: 12---64. Nenstiel's teachings
do not limit these benefits to one stage of a compressor. Rather, Nenstiel
teaches to use a diffuser at an outlet of an impeller stage of a compressor to
control fluid flow at that stage as flow conditions change due to changing
load demands and changes in inlet guide vane openings. Id. at 5:28---64. We
agree with the Examiner that skilled artisans would have been motivated by
such teachings of the benefits of using diffusers to control fluid flow at an
impeller outlet (stage) of a centrifugal compressor to use a diffuser at each
impeller outlet of Conry' s multi-stage compressor to obtain similar benefits.
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Appeal2017-009593
Application 14/383,750
This is particularly true where Conry teaches a multistage compressor
control system that senses and controls the flow of fluid through each stage
of a two-stage compressor to provide desired output and efficiency. Indeed,
Conry teaches the need to control or adjust the fluid flow rate at each stage
of the compressor in response to different loads, e.g., by using inlet guide
vanes at the inlet of each impeller stage and by using control logic to adjust
the inlet guide vane positions so that the compressor operates at very high
efficiencies over a wide range of loads. Conry, 2 :26-31; 5 :45---6:4, 7: 1-8: 1.
Conry also teaches to provide the second gas inlet of the second impeller of
the second stage with guide vanes to provide the necessary degree of control
for a particular compressor size. Id. at 5: 10-17. Conroy thus teaches to
configure each impeller stage with the same flow control devices, e.g., inlet
guide vanes, to control fluid flow more precisely at each impeller stage and
also to improve the overall efficiency of the multi-stage compressor.
N enstiel' s teachings complement those of Conry. N enstiel teaches the
benefits of using a diffuser at an impeller stage outlet to control the flow of
fluid through and from the impeller in response to changes in the fluid flow
due to changing loads and changes in the inlet guide vanes at the impeller
inlet. Nenstiel, 5:28---64. When the inlet guide vanes are adjusted to allow a
higher flow for greater load conditions, the diffuser gap is increased. As the
compressor load decreases, the inlet guide vanes decrease the fluid flow to
the impeller inlet whereupon diffuser gap 134 is reduced to decrease the area
at the impeller exit and thereby stabilize the fluid flow. Id. at 5:44---64.
These teachings indicate the benefits of adjusting inlet fluid flow via
guide vanes and outlet fluid flow via diffusers at each stage to control flow
more precisely, avoid surge, and improve efficiency at different loads.
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Appeal2017-009593
Application 14/383,750
Appellants' attorney arguments are not evidence and therefore do not
persuade us of error in the Examiner's reasoning, in light of the prior art's
teachings, that it would have been obvious to use flow control devices such
as diffusers at each stage of Conry' s compressor to control fluid flow at each
stage to avoid surge conditions, improve efficiency, and "provide the same
advantages as taught by Nenstiel which teaches a single diffuser." Ans. 2.
Further support for the Examiner's reasoning comes from Appellants'
own Specification. In the Background discussion of the prior art, Appellants
disclose that "[ m ]ulti-stage centrifugal compressors have used stages with
fixed, typically vaneless, diffusers with inlet guide vanes and variable speed
as the capacity control mechanism." Spec. ,r 4. Thus, Appellants disclose
the prior art's use of flow control devices like diffusers and inlet guide vanes
at each stage of a multi-stage compressor. This disclosure also supports the
Examiner's reasoning and confirms the prior art teachings discussed above.
Appellants' argument that Conry lacks diffusers because Conroy uses
inlet guide vanes, which would be removed if diffusers were added (Appeal
Br. 5) is not persuasive. Ans. 5. Conry and Nenstiel both use inlet guide
vanes to control inlet fluid flow. Nenstiel also uses diffusers with inlet guide
vanes to stabilize the outlet fluid flow and avoid surge. The Examiner uses
Nenstiel's diffusers with Conry's inlet guide vanes to control flow better as
Nenstiel teaches to do. Thus, we sustain the rejection of claims 1, 7, and 8. 2
2 In view of our affirmance of this rejection for the reasons presented, it is
not necessary to decide the propriety of the Examiner's alternative rationale
of "duplication of parts." If anything, this rationale appears to be a
shorthand method of describing the Examiner's more detailed rationale, as
discussed above, that the benefits taught by N enstiel for using diffusers in a
single-stage compressor likewise would apply to each stage of a multi-stage
compressor by stabilizing outlet flow at each stage. See Ans. 3, 5.
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Appeal2017-009593
Application 14/383,750
Claim 3
Rejected Over Conry, Shoemaker, Nenstiel, and Tetu
Dependent claim 3 recites "wherein the desired compressor pressure
ratio is about 10: 1." Appeal Br. 7 (Claims App'x). The Examiner finds that
Conry teaches to control the compression ratio. Final Act. 6. The Examiner
relies on Tetu to teach the recognition in the art that the maximum efficiency
of a compressor is achieved at or near a maximum pressure ratio, which is a
result-effective variable. Id. ( citing Tetu ,r 37). The Examiner determines it
would have been obvious to discover an optimum maximum compression
ratio such as a 10: 1 compression ratio through routine experimentation to
achieve peak compressor efficiency in view of these teachings. Id. at 6-7.
Appellants argue that the claimed impeller/ diffuser does provide a
compression pressure ratio of at least about 10: 1, and the Examiner has not
identified any prior art that teaches such a compression ratio. Appeal Br. 5.
This argument does not address the Examiner's rejection in the Final
Action, as discussed above. Therefore, it does not apprise us of error in the
Examiner's finding that the prior art teaches compression ratio as a result
effective variable that is used to achieve peak compressor efficiency. Nor
does it address the Examiner's reasoning that a skilled artisan would have
been motivated to experiment with different compression ratios to achieve a
maximum compressor efficiency and would have arrived at a compression
ratio of 10: 1 for a two-stage compressor through routine experimentation.
See Spec. ,r 21 (the compression ratio corresponds to a second stage outlet
pressure compared to a first stage inlet pressure).
Thus, we sustain the rejection of claim 3.
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Appeal2017-009593
Application 14/383,750
Claim 6
Rejected Over Conry, Shoemaker, Nenstiel, and Merola
Appellants argue that each dependent claim should be allowed based
on its dependence from an allowable base claim. Appeal Br. 5. Because we
sustain the rejection of claim 1, this argument is not persuasive, and we also
sustain the rejection of claim 6, which depends from claim 1.
Claims 9, 12, 14, and 15
Rejected Over Conry, Nenstiel, and Tetu
Independent claim 9 recites a refrigerant centrifugal compressor with
first and second impellers, a desired compression ratio of at least 10: 1, and a
diffuser at each of the first and second stage outlets. The Examiner relies on
Conry, Nenstiel, and Tetu to render obvious this subject matter based on the
same findings and reasons as for claims 1 and 3 above. See Final Act. 8.
Appellants rely on the arguments presented for claims 1 and 3 in their
argument for the patentability of independent claim 9. See Appeal Br. 3-5.
These arguments are not persuasive for the reasons discussed above, and we
sustain the rejection of claim 9. Because we sustain the rejection of claim 9,
we are not persuaded by Appellants' argument that claims 12, 14, and 15 are
allowable because they depend from an allowable base claim (see id. at 5),
and we also sustain the rejection of dependent claims 12, 14, and 15.
Claim 13
Rejected Over Conry, Nenstiel, Tetu, and Merola
The Examiner relies on Merola to teach an economizer in claim 13,
which depends from claim 9. See Final Act. 7-8. Appellants argue only that
claim 13 is patentable because it depends from an allowable base claim. See
Appeal Br. 5. Because we sustain the rejection of claim 9, this argument is
not persuasive, and we also sustain the rejection of claim 13.
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Appeal2017-009593
Application 14/383,750
DECISION
We affirm the rejections of claims 1, 3, 6-9, and 12-15.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a)(l )(iv).
AFFIRMED
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