Note: Descriptions are shown in the official language in which they were submitted.
The invention relates to a gear pump or motor having a
pinion stationarily ~ournalled in a body and an internally
toothed ring gear, meshing therewith and being yieldingly
. supported in the body, and more particularly to a gear pump
or motor, the body cavity thereof for the most part is on
high pressure.
It is an object of the invention to reduce bearing loads :
around the gears. :
,.
According to the invention there is provided a gear pump ~:
or motor comprising a body having a cavity and high pressure
and low pressure ports extending to said cavity, a pinion
having a shaft means journaled in the body for rotation of ~ :
; the pinion in said cavity, an lnternally toothed ring gear in
: said cavity and meshing with said pinion, said ring gear and `~
said pinion including an interspace therebetween, bearing .
means in said cavity interposed between the periphery of said
ring gear and said body ad~acent to said low pressure port .
for yieldingly.supporting said ring gear, said beàring means
. ., ., ~
. defining, at its outer face, a first arcuate area of low
: 20 pressure and, at its inner face, a second area of low pres- :
.. 3 sure, said first area being smaller than said second area and
,
said areas being connected to one another, a filling member
. in said interspace, said filling member having a sickle-
~ shaped cross section and subdividing said interspace into a
;; low pressure space which is connected to said low pressure ~ j
:. port and a high presure space which is connected to said high
pressure port r means for mounting said filling member and `
:. said ring gear ~or interspàce between said pinion and said :
.~ ring gear for pivotal movement and shifting movement trans-
.. . . ..
: 30 versely to the pivot axis, whereby said cavity is connected ~
. ~ ~
. to high pressure except for said low pressure space and said
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low pressure areas. ~ 5~
It i5 an advantage of the invention, at least in pre-
ferred forms, that it can compensate Eor leakage flow by
increasing the sealing effect when pressure increases.
A further advantage of the invention,~at least in pre-
ferred forms, is that it can reduce the noise produced in
operation of the machine. ~ `
The invention will be more apparent from the following
description of a preferred embodiment and accompanying
drawings, in which:
Figure 1 is a cross-sectional view taken along the line
B-B (Figure 2);
Figure 2 is a longitudinal sectional view along the line
A-A of Figure l;
Figure 3 i5 an enlarged fragmentary view of a portion of
the gear pump or motor filling member between an interspace
of gears; ;
Figure 4 shows an enlarged fragmentary section along the
line C-C of Figure 3;
Figure 5 shows the gears and some forces acting in the ~;
gear system; and
Figure 6 shows forces acting at the filling member.
Referring to Figure 2, a pump or motor body consists of a ~ ~d
front bearing plate 1, a first pump housing half 2, a second ~ -
pump housing half 3 and a rear end plate 4, which together
~ with O-sealing-rings 5, 6 and 7 seal the interior of the pump
- from the outside and are held together by means o~ bolts 8.
A pinion 9 is integrally connected to a pair of hollow
shafts 10 and 11, which are journalled in plain bearings 12
and 13 in the pump housing halves 2 and 3. The drive of the
. . .
~ pinion is via a splined shaft 14, which makes engagement with ~ ~-
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a corresponding spline in the hollow shafts 10 and 11, and is
held in position by means of a ball bearing 15 in the front
bearing plate 1. A conventional seal 16 seals, at the shaft
14, the interior of the pump from the outside.
The pump housing half 2 has a cylindr~ical cavity 17
(Figure 1), in which a ring gear 18 is located concen-
trically. Between the ring gear 18 and the wall of the pump
-housing half 2, there is an arcuate shell-shaped bearing
member 19, which encompasses the ring ~ear for a given ~-
10 angular extent to be explained below. Between the ring ge~r -~
18 and the pinion 9, a filling member 20 is located. A pin
` 21 is firmly connected with the filling member 20 and has two ;~
protruding ends 22 and 23 (Figure 4), having flattened
;parallel surfaces, each slideable in a groove 24 and 25,
respectively, which are provided in shafts 26 and 27, which
for their part are journalled in the housing halves 2, 3. A
pair of pressure plates 28 and 29 (Figures 1 and 2) are
provided to press axially onto the lateral sides of the
pinion 9 and the ring gear 18 around a low pressure space 33
20 and serve, as is conventional in the gear pump art, for axial `
compensation of any gaps, which might occur at the lateral
sides of the gears 9 and 18, between the suction or low
pressure space 33 and a high pressure space to be explained
below. `As pressure increases, the leakage flow will also
increase, however, the increased high pressure will urge the
pressure plates 28, 29 more tightly onto the lateral sides of
the gears 9, 18, thus decreasing the gap width and the
leakage flow passing therethrough. The pressure plates 28,
29 comprise holes, where the shafts 26, 27 are passing, and
30 are held against twisting by this holes-shaft-means. Two ~;
projections 30 and 31 (Figure 1) in axial direction at the
~ 3
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~ 5'~ Q
outer edge of each pressure plate 28 and 29 serve to prevent
movement, in the pumps rotary direc~ionj of the shell-shapsd
bearing member 19.
~ A low pressure or suction port 32 in the pump housing 2
has two bent passages extending, on axially and radially
~ curve~ ways (not shown), and through recesses (not shown) in
the plates 28, 29, into the very small suction or low
~; pressure space 33 proper of the pump. This low pressure
space 33 is delimited, in pump rotary direction, on the one ~-
. 10 hand by the filling member 20 and on the other hand by the ;
engagement place 34 of the gearings 9, 18.
A high pressure port 35 is extended directly through the :
pump housing 2 into the high pressure space of the pump,
which is formed by a ring space 36 between ring gear 18 and
cavity wall 17 - except for the bearing member 19 and the
. space taken by the pressure plates 28, 29, and by an inter-
,~ space 37 between the gearings 9, 18 - except for the filling
member 20 and the low pressure space 33. Sealing between the `~
. high and low pressure spaces is made by enagement of the
gearings at 34, at the filling member 20 and by the pressure ~ :
. plates 28, 29. The shell-shaped bearing member 19 has two
j~ arcuate suction fields or low pressure areas 38 and 39, which
: are connected to one another by a passage 41 and to the low
pressure port 32 by a passage 40. The outer low pressure
area 39 is smaller than the inner low pressure area 38. The
.. : .
j outer low pressure area is delimited by a seal which abuts at
5 ~ the inner wall of the cavity 17, while the inner low pressure ~ ::
~ area 38 is sealed from the high pressure space 36 by the `
i` sliding engagement oE surfaces 43 of the shell-shaped béaring
~`~ 30 member 19 with the ring gear 18.
The operation of the pump is as follows:
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lOS~30
If the pump is driven in the direction of rotation
indicated by arrows w, the space 33 between the gearings 9, ~ .
18 and the filling member 20 will be emptied, i.eO a low
pressure or suction effect becomes established in space 33..
- Liquid fed along the teeth gaps of the gearings 9, 18 will
enter into spaces 36, 36a, 36b, and 37 and create a high :
pressure which acts upon the lateral pressure plates 28 and
29, which are pressed against and make sealing contact to the -
.. side faces of the pinion 9 and the ring gear 18. Low ::
pressure, created in space 33, propagates through the bent ~ :
passages ~not shown) to the low pressure port 32 and, via the
passages 40, 41, into the low pressure areas 38, 39. Since
: area 38 is larger than area 39, the arcuate bearing member 19
will be forced or sucked toward ring gear 18 allowing, ~-
however, rotational movement of the latter. The angular
extent of the arcuate bearing member 19 is chosen to get the
low pressùre areas 38, 39 properly sized and angularly
~ directed, to create forces which will now be explained. -
This basi~ distribution of the low and high pressure ~?
20 areas and spaces leads to the arrangement of forces as
:~ indicated in Figures 5 and 6.
The pinion 9 is subject to a composite force Pl resulting
; . from the hydraulic force by the pressure space 37 and the :-:
tangential opposing force of driven gear 18. The ring gear
.:: 18 is subject to a composite force P2 resulting from the .:~
hydraulic force by high pressure space 37 and from the ;:
.~. .
driving force of the pinion 9. The ring gear 18 and the
bearing member 19 connected together by the suction forc~ of `-~ -
area 38, as a whole, are subject to a forcae P3, the size and ;;~
direction of which depends on the size and angular position 1~
of the outer low pressure area 39. The forces P2, P3 ..
- 5 -
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basically are opposed, and the angular position and extent of
the low pressure area 39 are to be chosen in such a way that
a small overall resultant force P4 on ring gear la is
obtained.
~ Ring geac 18 is supported by the pinion 9 at engagement
I point~34 and by the filling member 20, therefore, force P4
acts as a component force P5 on the pinion 9 and as a com-
; ponent force P6 on the filling member 20 with the advantage
~ of making a good sealing contact therebetween.
; 10 The forces Pl and P5 acting upon the pinion 9 make an
obtuse angle and are combined to a force P7, which is
supported by the bearings 12, 13 of the pinion 9. The
resultant force P7 is smaller than the force Pl, that is, a
reduction of the bearing load is brought about.
The active forces upon the filling member 20 are the
mentioned for~e P6 (by the ring gear 18), and a hydraulic
force P8 from the high pressure space 37. The force P8 is
perpendicular to the separating plane between the high and
low pressure spaces 37 and 33, respectively, i.e. normal to
the connecting line between such tooth tips of the ring gear ~
18 and of the pinion 9, which are in sealing contact to the -
filling member 20. Forces P6 and P8 form a resultant force ~`
P9, which is to be supported by the pin 21 and the pinion 9. ~;
The force P9 being divided up into lines going through `~ -
the pin 21 and the pinion 9, respectively, result in com
ponent forces P10 and Pll. Force P10 is perpendicular to the
surfaces of the pin ends 22 and 23 and is passing through the
- axis of the pin 21. Force Pll is the sealing force between `
the filling member 20 and the teeth tip ends of the pinion 9.
The force Pll is superposed to the force P7, which form a
final force P12, being further reduced in relation to force
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s P7. The final force P12 is to be taken up by the bearings
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10, 11 and it is remarkable that this force is much smaller
than Pl, which would be the basic load of the bearings 12, 13.
The position of the pin 2l is so arranged that the fiorce
P9 does not cross the pin 21, but instead runs outside of it,
that is to say towards the ring gear 18. This makes it sure
that a good sealing contact is created around the low pres-
sure space 33, i.e. all parts of the overall system come into
engagement to close gaps. Therefore, a high efficiency of
the pump is attained and the pumps operate quietly in all
operational conditions.
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