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Патент USA US3072326

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Jan. 8, 1963
K. B. MOSSIN
3,072,315
ROTARY PUMP OR EXPANSION ENGINE
Filed July 8, 1958
‘
3 Sheets-Sheet 1
Jan. 8, 1963
K. B. MOSSIN
3,072,315
ROTARY PUMP OR EXPANSION ENGINE
Filed July 8, 1958
3 Sheets-Sheet 2
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Jan. 8, 1963
K. B. MOSSIN
' 3,072,316
ROTARY PUMP 0R EXPANSION ENGINE
' Filed July 8, 1958
3 Sheets-Sheet 3
INVENTOR
/
KQ'Z Barge, Moss/‘A1
ATTORNEYS‘
grates
" atent O M C@
1
3,072,316
Kai Bérge Mossin, Hellerup, Denmark, assignor to Novo
Terapeutisk Lahoratorium A/S, Copenhagen, Den
ROTARY PUMP 0R EXPANSION ENGINE
mark
Filed July 8, 1958, Ser. No. 747,287
Claims priority, application Denmark July 15, 1957
5 Claims. ((31. 230-150)
The present invention relates to a rotary pump or ex
pansion engine comprising two rotors rotating in opposite
3,072,316
Patented Jan. 8, 1963
2
According to the invention, the periphery of the single
tooth rotor preferably comprises a ?rst sector concentric
with the axis of rotation of this rotor for cooperation
with the circular-arc-shaped crown of each of the teeth
of the double-tooth rotor, and an oppositely located sec
ond sector which is likewise concentric with the axis of
rotation and forms the crown of the tooth of this rotor.
During the operation, said ?rst sector will roll or slide on
the tooth crowns of the double-tooth rotor, so that at
this point a considerable sealing can be obtained, and at
the same time the second sector of the single-tooth rotor
will over a considerable angle cooperate with the wall
of the working compartment of this rotor, so that at
directions in a case which in cross section has the shape
of two mutually overlapping circles, one of said rotors
having one tooth and being convex in cross section, at any
this point there will also be a great resistance against
rate as regards the greater part of it, and rotating on an
passage from the high-pressure side to the low-pressure
axis eccentric in relation to the geometrical centre of the 15
side.
cross section, while the other rotor has two teeth and
The periphery between the tooth crowns of the double
rotates on an axis, which is centric in relation to the geo
tooth rotor is according to the invention advantageously
metrical centre of the rotor cross section, at a rate of
formed by at any rate substantially concave faces with
revolution equal to halt the number of revolutions of the
former rotor.
Such rotary pump or expansion engine is for example
known from the speci?cation of British Patent No. 663,
substantially the same curvature as the crown of the tooth
20 of the single-tooth rotor. An advantage of this arrange
ment is that the pressure of the working ?uid on the
double-tooth rotor may be distributed tolerably evenly in
928 which in detail describes an embodiment with a single
the position of the rotors corresponding to the highest
tooth rotor and a triple-tooth rotor, but also discloses that
the triple-tooth rotor may be substituted by a double 25 pressure of the working ?uid, and hereby a turning mo
ment on the double-tooth rotor caused by the working
tooth rotor which in cross section approximately has the
?uid can be avoided.
shape of a rectangle, the length of which is of the same
In a preferred embodiment of the rotary pump or the
size as the diameter of the cylindrical working space of
this rotor.
The two short sides of the rotor cross sec
expansion engine according to the invention the crowns
of the teeth of the double-tooth rotor continue into the
tion are not rectilinear, however, but are formed by circu~ 30 ?anks of the teeth through short transition roundings
lar arcs with a diameter corresponding to the width of
which form line sealing against the single-tooth rotor
the rotor cross section. During the operation, the two
over the greater part of the periphery of the latter.
co-operating rotors are at any time in contact with each
During the operation of the pump or engine the line of
other along at least one line, and each of the teeth on
the multi-tooth rotor furthermore forms a line sealing 35 contact between the two rotors will “linger” at the said
along the wall of the working space of this rotor. The
single-tooth rotor may in a similar way be in line contact
with the wall of the working space of this rotor, but may
also be so formed as to touch the said wall over a sector
of egg. about 30°.
The construction referred to in the said patent speci?ca
tion is stated to have a smaller clearance space than the
transition roundings and so to speak skip the substan
tially concave faces of the double-tooth rotor.
In an expedient embodiment of the rotary pump or ex
pansion engine it is of the type (known for example from
40 the British patent speci?cation mentioned above) where
inlet and outlet channels for the working ?uid terminate
in the working space through slot-shaped openings in the
vicinity of the ‘point of intersection of the circles deter
rotary pumps or expansion engines known in advance and
mining the cross section of the working space, at any rate
thus a better e?iciency than the latter.
the
one of the said channels, in which the Working ?uid
45
The present invention is based on the cognition that
is under the highest pressure, terminating in the working
a further considerable reduction of the clearance space
compartment ‘for the double-tooth rotor and containing a
may be obtained together with other advantages when the
valve which is located close to the said working compart
double-tooth rotor in cross section has substantially the
ment and is operated in time with the rotor. ‘In this case
form of a double-bitted battle-axe, the crown of each
tooth being formed by a circular-arc shaped part of the 50 the opening of the latter channel is, according to the
present invention, advantageously in permanent commu
periphery of the rotor with its centre in the centre of the
cross section thereof and with a comparatively consid
erable extent in the peripheral direction, while the width
of the cross section of the tooth at any rate in the outer
portion ofeach tooth decreases towards the centre.
An advantage of this construction (in addition to the
reduction of the clearance space) consists in that the
sealing zone between each of the teeth of the double-tooth
rotor and the wall in the associated working compart
ment extends over a considerable sector or arc, which
gives a better sealing between the tooth and the wall
nication with the working compartment of the single~tooth
rotor at a point near this opening.
The permanent com
munication may for example vbe provided by cutting away
55 parts of the wall of the working compartment of the dou
ble-tooth rotor between the opening of the channel and
the Working compartment of the single-tooth rotor. This
permanent communication will certainly, whether it be
provided by the said cutting away or in some other way,
60 entail an increase of the clearance space in the pump or
expansion engine, but, ?rstly, this increase need only be
rather insigni?cant and, secondly, the permanent com‘
munication possesses the special advantage that the pres
sure ?uid from the working compartment of the single
have no ?rm abutment on or firm contact with the latter.
The wide contact face between the crown of the tooth 65 tooth rotor may ?ow evenly into the Working compart
ment of the double-tooth rotor so that no passage losses
and the wall of the working compartment furthermore
will occur. ,
opens up the prospect of designing shallow sealing grooves
than in the case of linear contact for the reason that
the tooth is to slide along the wall and therefore can
The invention will now be more fully described with
in at least one of the co-operatiug faces for the further in
reference to the drawing, in which:
crease in the resistance against the passage of the work
ing ?uid from the high-pressure side of the tooth to its 70 FIG. 1 illustrates a diagrammatical cross section
low-pressure side.
through an embodiment of the machine with the two
8,072,316
3
41.
rotors and the associated rotary valve in a ?rst position,
FIGS. 2 and 3 are similar views of the same elements
in two other positons during operation,
KG. 4 is a fragmental sectional view of a slightly modi
?ed embodiment of the invention, and
' FIG. 5 is an almost similar fragmental view of a fur—
ther embodiment.
’ In the drawing, 1 designates the case of the apparatus
which comprises two partly overlapping cylindrical work
,
sealing contact with the right-hand curved portion 11
of the single-tooth rotor h. At the same time the op
posite tooth crown on the [rotor 13 has cut of? the com
munication from the inlet channel 4 to the chamber
above the rotor
This chamber is, however, via the
outlet opening a, which is obstructed by the rotary valve
8, and the recess 17 in permanent communication with
the compression chamber in the cylinder or compart
ment 2, so that during the rotary motion of the rotors
a uniform rise in pressure will occur in the intercom
ing compartments 2 and 3. An inlet or admission chan
municating chambers. If the recess 17 were not pro~
nel 4 terminates 'in the interior of the case through a
vided, the right-hand tooth of the (rotor 13 would form
slot-shaped opening 5 which in the embodiment shown
a separation between the two chambers during the ?rst
is in communication with both working compartments 2
part of the compression stroke, and the passage of the
and 3, but may also be in communication with only one
15 working ?uid from the compartment 2 to the compart
of the said two working compartments.
ment 3 would not commence until a‘ pressure of a certain
Opposite the inlet opening 5 there is in the wall of the
value had been produced in the compartment 2,‘ and
working ‘compartment 3 formed an outlet or discharge
therefore the sudden opening for the passage would be
opening 6, the communication of which with an outlet
accompanied by a certain throttling loss.
channel 7 is controlled by a rotary valve 8 which is suit
FIG. 2 shows the position of the different parts after
ably accommodated in the outlet channel 7 and the cir~
the single-tooth rotor 9 and the rotary valve 8 have
cular-arc-shaped sealing face of which co-operates with
turned about 180° from the position in FIG. 1, while
comparatively small sealing faces above and below the
at the same time the double-tooth rotor 13 has turned
slot-shaped outlet opening 6, respectively.
slightly less than 90°. In the position in FIG. 2 the
In the working compartment 2 there is on a centrally
'journalled shaft lit) mounted a rotor 9, the cross section 25 rotary valve has opened the outlet opening 6, and the
working ?uid is being forced out into the outlet channel
periphery of which comprises a ?rst sector a, which is
7, the lower tooth crown 14 on the double-tooth rotor
concentric with the axis of rotation of the rotor, i.e. the
meanwhile being in sealing contact with the circular sec
axis of the shaft it), and has a radius which is consider
tor a of the single-tooth rotor 9. The opening point
ably smaller than half the diameter of the working com~
partment 2, e.g. about one half of half the diameter of 30 for the rotary valve 8 may be adapted to the pressure
which it be desired to produce.
the latter, and a second sector 12 which is concentric with
the same axis and the radius of which is equal to half the
diameter of ‘the working compartment 2.
The two sec
In FIG. 3 the different parts approach their positions
at the termination of the compression stroke.
The circu
Centrallyin the working compartment 3 a shaft 1?; is
lar section b of the single-tooth rotor 9 still seals against
tie‘ wall of the working compartment 2, and the left
hand curved portion 11 of this rotor is in line contact
journalled which carries a double-tooth rotor 13 which
in cross section is shaped like a double-bitted battle-axe,
with the left-hand lower corner rounding of the double
tooth [rotor ‘13. The rotary valve 8 has partly obstructed
tors a ‘and b are interconnected through curved por
tions 11.
the cross section being bounded by two circular arcs 14,
which are concentric with the axis of the shaft 12‘, and
two concave arcs 15 connecting the said arcs 14.
These
the outlet opening 6, but pressure ?uid may still how
out through this opening. From the position in FIG.
3 the parts turn on, and the left-hand end of the circu~
concave arcs 15 may be substantially circular-arc-shaped,
lar-arc-shaped sector b reaches the lower, left-hand
in which case their radius of curvature is of the same size
corner rounding lid of the double-tooth rotor 13, so
that the space between the two rotors, ie. the clearance
space of the machine, has reached its minimum. At
as or slightly smaller than the radius of the sector b of
the single-tooth rotor 9. The tooth crowns 14,‘ of the
double-tooth rotor 13 therefore have a considerable extent
in the circumferential direction which, as explained in
this point, the rotary'valve 3 completely obstructs the
outlet opening 6, and the whole of the concave, down
wards-facing side or ?ank 15 of the double-tooth rotor
13 will be loaded with the pressureof the working
the foregoing, makes possible a particularly effective seal
ing between these tooth crowns and the wall of the working
compartment 3 and, as also mentioned before, this sealing 50 medium so that the latter exerts no unbalanced stress
on this rotor. During a very short further turning of
may be further improved ‘by means of shallow grooves or
the parts the line of contact between the two rotors 9
corresponding irregularities on at least one of the co
and 113 “skips” to the right-hand lower corner round
operating ‘faces. Such grooves extending in the ‘axial
ing 16 of the rotor 13, which rounding will during the
direction of the rotor 13 have been indicated in FIG. 4.
Therotor 13 has in the embodiments shown short tran 55 further turning slide on the right-hand curved portion 11
of the single-tooth rotor 9. The parts have now arrived
sition roundings 16 between each of the tooth crowns 1'4
into a position corresponding to that shown in FIG. 1.
and the tooth ?anks 15.
It will be obvious that the apparatus illustrated in the
Between the outlet opening 6 and the working com
drawing may also work as an expansion engine, this
partment 2 a permanently open passage 17 is provided
for the purpose explained in the ‘foregoing. In the illus 60 only necessitating that the rotary valve 8 is given a
trated embodiments, this passage is formed by one or
more recesses extending through the portion or" the cas~
ing 1 separating the opening 6 from the compartment 2.
rotary motion in the opposite direction to the arrow
shown and that pressure ?uid is supplied to the channel
7. The two rotors 9 and 13 will then by the pressure
medium be given a rotary motion in the direction op
When the apparatus shown is to operate as a rotary
>
pump, the rotors v9 and 13 and the rotary valve % are 65 posite to the arrows shown.
The turning valve 8 in the outlet channel 7 shown in
caused to rotate in the directions indicated by the
FIGS. 1-3 oifers favorable discharge possibilities, but
arrows and in such a way that the rate of revolution for
also valves of other types may be used. Thus, in FIG.
the rotor 13 is half the rate of revolution for the rotor
4 a spring-loaded non-return valve 18 has been shown
9, the rate of revolution ‘of which is equal to the rate
which is hinged as at 19 to a portion of the casing 1 and
of, revolution ‘for the rotary valve 8.
In the position in FIG. 1, the sector b of the single
tooth rotor has just cut off the communication from
the‘inlet channel 4- to the compression chamber in the
cylinder or compartment 2, and the right-hand lower
transition ‘rounding of the double-tooth rotor 13 is in 75
is permanently urged towards its closed position by
means of a compression spring 20 inserted between an
appropriate part of a casing 1 and an arm 22‘ rigidly
connected with the valve plate 18.
‘
In FIG. 5' a transversely displaceable‘gate valve 22
3,072,310
5
6
has vbeen shown. By an appropriate mechanism (not
shown) of conventional type, this gate valve or slide
said second sector and said further sections of the ?rst
rotor and said second pair of opposite sectors of the
valve may be moved between a closing position and an
second rotor being interrelated in such a manner that
open position indicated by broken lines in FIG. 5.
during operation the rotors contact each other at least
FIG. 4 also indicates that provisions may be made for Cl along a single line at all times, inlet and outlet ducts
cooling the machine during its operation, particularly
in said casing located one on each side of the second
when the machine is a high pressure rotary pump.
rotor and communicating with said working space and
Thus, reference numerals 23 and 24 in PEG. 4 designate
sealed from each other by the rotors, and a control
cooling ?uid passages provided in the casing 1 of the
valve disposed in that one of said ducts in which the
machine.
10 highest working pressure prevails during operation.
Finally should be mentioned that due to the spcciai
2. A rotary machine as claimed in claim 1, wherein
cross sectional shape of the double-tooth rotor with
each central portion of each sector of said second pair
comparatively deep cuts between the teeth the single
of ‘sectors of said second rotor has substantially the
tooth rotor may have an especially high ratio between
same curvature as said second sector of said ?rst rotor.
its largest radius (sector 11) and its smallest radius .
(sector a), which results in a correspondingly large
cross sectional area ‘for the compression chamber or
3. A rotary machine as claimed in claim 1, wherein
each of the sectors of said ?rst pair of opposite sectors
of said second rotor continues into the adjacent ends of
the expansion chamber and consequently a high output
said second pair of sectors through short transition
per unit of length of the rotors.
roundings which ‘form line contact with said further
I claim:
20 sectors of said ?rst rotor during operation.
1. A rotary pump or expansion engine, having a cas
4. A rotary machine as claimed in claim 1, wherein
ing enclosing a working space comprising two inter
one of the inlet and outlet ducts in which the highest
secting compartments of circular cross-sectional shape,
working pressure prevails during operation communi
a ?rst rotor journalled for rotation Within one of said
cates with said other compartment of the working space
compartments about the axis thereof and having a
through a slot-shaped opening in the vicinity of one of
peripheral surface of cylindrical formation, the cross
the points of intersection of said compartments, a rotary
section of which is composed of a ?rst sector concentric
valve controlling said opening and being located in
with said axis and of a radius considerably smaller than
close proximity to said other compartment and operated
the radius of the particular compartment, a second
in properly timed relation with said rotors, and said
sector concentric with said axis and of substantially the
opening below said valve communicating with the com
same radius as said compartment, and two convex
partment within which said ?rst rotor operates, through
further smoothly curved sections interconnecting the
at least one permanently open passage terminating in
the latter compartment in the vicinity of said point of
respective ends of said ?rst and second sectors, said
intersection.
further sections having end portions extending tangential
to respective ends of said ?rst and second sectors, a
5. A rotary machine as claimed in claim 1, wherein
second rotor journalled for rotation within the other
the peripheral faces of said second rotor, corresponding
one of said compartments about the axis thereof and
with said ?rst pair of opposite sectors, are roughened.
having a peripheral surface of cylindrical formation,
References Cited in the ?le of this patent
UNITED STATES PATENTS
the cross section of which is that of a double bitted
battle-axe and composed of a ?rst pair of opposite sec
tors concentric with the axis of said other compartment
and of substantially the same radius as this compart
ment, and a second pair of opposite sectors of a gen
erally concave formation interconnecting the respective
ends of the sectors of said ?rst pair of opposite sectors,
45
each sector of said second pair of opposed sectors hav
ing a generally flat central portion and arcuate end
portions, the spacing of said axes being equal to the
combined radii of said ?rst rotor ?rst sector and said 50
second rotor ?rst sector, a driving connection between
said two rotors causing said second rotor to revolve in
operation in the opposite direction from that of said
?rst rotor and with a rotational speed equal to one half
of the rotational speed of said ?rst rotor, the shapes of 65
508,574
Lambing __________ __ Nov. 14, 1893
595,227
1,698,802
1,821,523
2,198,786
2,698,130
2,920,610
Wattles ____________ __ Dec. 7, 1897
Montelius __________ __ Jan. 15, 1929
Montelius ____________ __ Sept. 1, 1931
Mossin ____________ __ Dec. 28, 1954
Breelle ______________ __ Jan. 12, 1960
20,174
Great Britain ____________ __ of 1909
663,928
604,302
323,492
Great Britain ________ __ Dec. 27, 1951
France ____________ __ Jan. 25, 1926
Montelius __________ _._ Apr. 30, 1940
FOREIGN PATENTS
721,481
Italy ______________ __ Dec. 24, 1934
Germany __________ __ Feb. 19, 1943
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