COMMISSIONER'S DECISION
Obviousness: Magnetizable Fluid Bearing
Use of ferromagnetic fluid as a journal bearing, lubricant when subjected to a
magnetic field is shown the prior art. Applicant uses ferromagnetic fluid
in a combined journal and thrust bearing arrangement. This was found to be
obvious. A special sealing arrangement for the fluid was held to be allowable.
Final Action: Modified, claims 1 to 10 rejected, claims 11 and 12 allowed.
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This decision deals with a request for review by the Commissioner of
Patents of the Examiner's Final Action dated March 79, 1976, on applica-
tion 160,525 (Class 308-1.6). The application was filed on January 4,
1973, in the name of John C. Stiles et al, and is entitled "Lubrication."
The Patent Appeal Board conducted a Hearing on September 21, 1917, at which
Mr. J. Nelson Landry represented the applicant.
This application relates to a lubrication technique which serves as a bear-
ing to alloy: movement of two surfaces relative to one another. A magnetizable
fluid is used in the gap between the two surfaces and a sufficiently strong
magnetic field is applied which allows the fluids to maintain the surfaces
out of contact. Figure 3 of the application is illustrative of the invention:
<IMG>
In the Final Action the examiner rejected the claim of this application
for failing to define patentable subject matter over the following patent:
United States
3,439,961 April 22, 1969 Stiles
The Stiles patent relates to a bifluid hydrodynamic bearing wherein a
ferromagnetic fluid is used as a bearing lubricant. Means for magnetizing
the fluid are provided by electrically energized coils. Figure 1 of Stiles
is shown below:
<IMG>
Claim 1 of that patent reads as follows:
A hydrodynamic bearing for a free rotor gyro, comprising an
inner bearing element; an outer bearing element, coaxial with
said inner bearing element and spaced therefrom to provide a
bearing cavity; a fluid lubricant supported therebetween,
having poor wetting characteristics; and, axially-spaced non-
wettable means attached to said inner and said outer bearing
elements at the ends of the bearing, cavity for trapping
said fluid within the bearing cavity.
In that action the examiner stated (in part) as follows:
Applicant discloses and claims as his alleged invention the
combination of movable elements with a magnetizable fluid in
a constraining magnetic field as the only lubricant within a
gap between all surfaces of the elements requiring lubrication
(claim 1). A specific application is in the field of self-
lubricating bearings wherein the only lubricant is a magnet-
izable fluid as defined in claim 6. More specifically such a
bearing may be a journal or radial bearing as defined in
claims 10 or 12.
The Stiles reference can be seen from the drawings and disclosure
to show a combination thrust and journal bearing. The thrust
bearing operates as an aerodynamic bearing by using air 34
between the relatively moving surfaces (thrust collar at end of
shaft 16 and its associated housing, as seen on the right-hand
side of Figure 1.)
The journal or radial bearing may operate as described on column
3 lines 24 to 46 inclusive of the disclosure from which it is
clearly evident that fluid 24 carrying ferromagnetic particles
54 is the only bearing lubricant between radial bearing surfaces
42 and 36. Coils 56 produce the magnetic field to maintain the
fluid in the bearing cavity 38.
Thus the hydrodynamic journal bearing acts to carry or support
radial loads while the aerodynamic thrust bearing supports axial
loads. In Stiles, the ferromagnetic fluid serves the added
function of sealing off the air 34 in the high pressure chamber
20 from leaking to the low pressure chamber.
With reference to the more specific form of claims such as 10
or 12 which relate to a journal bearing, as such, it is clear
that these claims read on the journal bearing of Stiles. Con-
sequently, this is also true of the broader claims 1 and 6 which
could cover either a journal bearing per se, a thrust bearing
per se or the combination thereof.
Applicant submits (page 2 of his latest remarks) that the entire
assembly as seen in figure 1 is a simple bearing because one
without the other would be an inoperative device. While this
may be true under the conditions in which the Stiles device
operates, nevertheless it is held that there is no invention in the
use of only the journal bearing of Stiles without the thrust
bearing under conditions where only radial loads apply (as implied
in the reverse case, that is, the use of the only the thrust bearing
of Stiles without the journal bearing under essentially thrust
load conditions. The elimination of any part with its correspond-
ing function, where conditions permit, is not patentable.
It is interesting to note that claim 3 of the Stiles patent defines
a bearing using a magnetizable fluid as the sole lubricant and the
use of a second fluid is not claimed except in claim 6, in the
form of assisting the bearing function of the hydrodynamic bearing.
It is seen that the structure of a broad claims such as 1 and 6
herein and the specific journal claims 10 and 12 would infringe
the structure recited in claim 3 of the Stiles patent.
In response to the Final Action the applicant submitted an amended set
of claims and stated (in part):
In the substitute claims it is to be noted that the Applicant has
restricted the scope of all claims to a combined thrust-and-journal
bearing. Claim 1 of the enclosed claims as based on former Claim 2 and
noted that, in order to facilitate examination, numerous dependent
claims of lesser importance have not been included in the enclosed new
set of claims.
Since all of the amended claims submitted herewith refer to a combined
thrust-and-journal bearing, Applicant submits that they are no longer
susceptible of interpretation that they read on the applied reference,
United State Patent No. 3,439,961 (Stiles). This is so, because,
in accordance with the Examiner's interpretation, the claims were
allegedly readable on a journal bearing of this reference. Even though
Applicant cannot share the Examiner's opinion that it is proper
to speak about a journal bearing in the Stiles patent, because there
is only a combined bearing disclosed, the restriction to a combined
thrust-and-journal bearing emphases the distinction, ~nasmuch as
the thrust portion of the combined bearing by Stiles is an aerodynamic
bearing portion.
In view of the restricted scope of the claims presented here-
with, Applicant believes that the objectionable matter has
been removed, that the final objection has been overcome and
that the application is in condition for allowance.
The issue to be considered by the Board is whether or not the applicant
has made a patentable advance in the art over the cited references. Amend-
ed claim 1 reads as follows:
A combined thrust-and-journal bearing comprising structural
elements mounted for motion of a surface of one element along
a surface of another element, with a lubricant within a gap
between the surfaces, wherein the only lubricant between all
surfaces requiring lubrication is a magnetizable fluid, the
magnetizable fluid forming it's own sealing medium by virtue
of a magnet is field which causes portions of the magnetizable
fluid to be attracted toward every opening of the gap.
Considering the Stiles citation we find that the concept of using a magnetizable
fluid lubricant and electromagnetic means to create a magnetic field to
maintain the fluid in position between moving surfaces is known. This patent
also shows the use of pressurized air to provide a bearing arrangement to
compensate for the thrust force. It is the applicant's contention that his
combined thrust and journal bearing, which uses only magnetizable fluid for
both functions, is a patentable advance in the art.
The applicant argues that the hydrodynamic bearing disclosed by Stiles as
a single bearing wherein the "so called gas bearing" acts as a thrust bearing
which is not independent of the radial magnetic fluid bearing since they both
form part of the same assembly. Considering the force components involved in
Stiles we conclude that rotary motion of the shaft 16 would generate radial
force and an axial end load on this shaft would produce the thrust force.
These are two separate and distinct force factors, While it is desirable to
have a unitary bearing capable of overcoming both component factors it dies
not necessarily have to be one assembly. Clearly Stiles does show the use
of a magnetic fluid bearing for radial force, but it will operate in this mode
irrespective of the thrust bearing arrangement that is located in the adjacent
area.
Applicant's amended claims, which were submitted in response to the Final
Action, specify a combined thrust and journal bearing wherein the only lubri-
cant between all bearing surfaces requiring lubrication is a magnetizable
fluid, and wherein the magnetizable fluid forms its own sealing medium by
virtue of a magnetic field. Stiles also seals the fluid with no contact
between the shaft and housing "by a magnetic field so that the fluid may be
maintained within the bearing cavity and not leak out from the ends."
Figure 1 of Stiles supra shows the use of magnetizable fluid for the journal
bearing area with the coils for producing the magnetic field which prevents
leakage.
Claim 1 of Stiles specifies "an outer bearing element coaxial with said inner
bearing element and spaced therefrom to provide a bearing cavity; a fluid
lubricant supported therebetween...." This claim covers either a journal or
radial bearing arrangement that would be used in this manner. Amended
claim 1 specifies a combined thrust and end bearing with one magnetizable
fluid which forms a sealing medium when subjected to a magnetic field. The
concept of a magnetizable fluid bearing is disclosed in Stiles. The practical
application is a difference in design or layout only. In our view no result
has been achieved which can be considered to have flowed from an inventive
step and we recommend claim 1 be refused. Claims 2 to 4 which depend on
claim 1, add the magnetic field in combination with the bearing and this
does not render these claims patentable over refused claim 1.
Claim 5 specifies a self lubricating combined thrust and journal bearing
wherein the only lubricant is a magnetizable fluid. We recommend that
this claim be refused as the arguments applied to claim 1 apply equally to
it. Claims 6 to 10, which depend on amended claim 5, detail the magnetic
force providing means. These claims do not define patentable subject matter
over refused claim 5.
Claims l1. and 12 are directed to specify sealing arrangement in conjunction
with the magnetizable fluid means which, in our opinion, is a new combination
that represents a patentable advance over the cited art. These claims
appear allowable. They must however, be submitted in proper form as
claims 1 and 2.
In summary, we recommend that claims 1 to 10 be refused, but that claims
11 and 12 are allowable.
J.F. Hughes
Assistant Chairman
Patent Appeal Board, Canada
I have reviewed the prosecution of this application and I concur with
the recommendation of the Patent Appeal Board. Accordingly, I refuse to
grant a patent on claims 1 to 10. I will however, accept claims 11 and
12 when presented as claims 1 and 2. The applicant has six months within
which to make the appropriate amendment, or to appeal this decision under
the provision of Section 44 of the Patent Act.
J.H.A. Gariepy
Commissioner of Patents
Dated at Hull, Quebec
this 14th. day of October, 1977
Agent for Applicant
Ogilvy, Cope, Porteous, Montgomery,
Renault, Clarke & Kirkpatrick,
Suite 700, The Royal Bank Bldg.
1 Place Ville Marie
Montreal, Quebec H3B 1Z7