U.S. patent application number 09/726974 was filed with the patent office on 2001-11-15 for gearing with mating internal and spur gears.
This patent application is currently assigned to LuK Lamellen und Kupplungsbau GmbH. Invention is credited to Buchmuller, Klaus-Dieter, Grethel, Marco.
Application Number | 20010041144 09/726974 |
Document ID | / |
Family ID | 7931882 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010041144 |
Kind Code |
A1 |
Buchmuller, Klaus-Dieter ;
et al. |
November 15, 2001 |
Gearing with mating internal and spur gears
Abstract
A gearing, particularly for use in a gear pump which can be
utilized in the power train of a motor vehicle, has a housing, a
rotary internal gear in the housing, and a spur gear driven by a
prime mover, mating with the internal gear and defining with the
latter a crescent-shaped chamber for forcible conveying of a fluid,
such as lubricant, from an inlet communicating with one end portion
to an outlet communicating with the other end portion of the
chamber. In order to avoid turbulent flow of fluid in the chamber,
the latter is substantially filled by a composite insert. Such
insert can comprise several crescent-shaped fillers with at least
one seal between them, or two one-piece or composite fillers which
are disposed end-to-end as seen in the circumferential direction of
the internal gear and are separated from each other by an abutment
which is secured to or of one piece with the housing.
Inventors: |
Buchmuller, Klaus-Dieter;
(Malsch, DE) ; Grethel, Marco; (Buhlertal,
DE) |
Correspondence
Address: |
Darby & Darby P.C.
805 Third Avenue
New York
NY
10022
US
|
Assignee: |
LuK Lamellen und Kupplungsbau
GmbH
|
Family ID: |
7931882 |
Appl. No.: |
09/726974 |
Filed: |
November 30, 2000 |
Current U.S.
Class: |
418/126 ;
418/170 |
Current CPC
Class: |
F04C 2/101 20130101 |
Class at
Publication: |
418/126 ;
418/170 |
International
Class: |
F01C 019/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 8, 1999 |
DE |
199 59 215.2 |
Claims
What is claimed is:
1. A gearing comprising: a housing; an internal gear rotatably
mounted in said housing; a spur gear rotatably mounted in said
housing, mating with said internal gear and defining with the
latter a substantially crescent-shaped chamber; means for rotating
one of said gears to thus rotate the other of said gears; and an
insert provided in and at least substantially filling said chamber,
said insert including a first filler, at least one abutment for
said first filler, and a second filler.
2. The gearing of claim 1, wherein said at least one abutment is
disposed between said fillers, as seen in a circumferential
direction of said internal gear.
3. The gearing of claim 1, wherein at least one of said fillers has
an outline resembling a portion of said substantially
crescent-shaped chamber.
4. The gearing of claim 3, wherein said at least one filler
occupies approximately one-half of said chamber.
5. The gearing of claim 3, wherein each of said fillers has an
outline resembling a portion of said substantially crescent-shaped
chamber and each of said fillers occupies approximately one-half of
said chamber.
6. The gearing of claim 1, wherein at least one of said fillers
comprises a plurality of discrete sections.
7. The gearing of claim 1, wherein one of said fillers comprises a
plurality of sections.
8. The gearing of claim 7, wherein the other of said fillers is of
one piece.
9. The gearing of claim 1, wherein said chamber has first and
second end portions spaced apart from each other in a
circumferential direction of said internal gear, said housing
having an inlet communicating with one end portion and an outlet
communicating with the other end portion of said chamber.
10. The gearing of claim 9, wherein one of said fillers is adjacent
said inlet and the other of said fillers is adjacent said
outlet.
11. The gearing of claim 10, wherein said abutment is rigid with
said housing and is disposed between said fillers, as seen in said
circumferential direction.
12. The gearing of claim 1, wherein said housing forms part of a
pump.
13. The gearing of claim 1, wherein said one gear is said spur
gear.
14. The gearing of claim 1, wherein said at least one abutment is
rigid with said housing and is located between said fillers, as
seen in a circumferential direction of said internal gear, one of
said fillers comprising discrete first and second sections and at
least one sealing element between said sections.
15. The gearing of claim 1, wherein said means for rotating
comprises a power-driven drive spline and a complementary internal
spline provided in said spur gear and meshing with said drive
spline.
16. The gearing of claim 1, wherein said crescent-shaped chamber
has first and second end portions spaced apart from each other in a
circumferential direction of said internal gear, said housing
having an inlet communicating with one of said end portions and an
outlet communicating with the other of said end portions, said spur
gear having an annulus of external teeth and said internal gear
having an annulus of internal teeth mating with said external teeth
in a region adjacent one of said inlet and said outlet.
17. A gearing comprising: a housing; an internal gear rotatably
mounted in said housing; a spur gear rotatably mounted in said
housing, mating with said internal gear and defining with said
internal gear a substantially crescent-shaped chamber; means for
rotating one of said gears to thus rotate the other of said gears
by way of said one gear; and a substantially crescent-shaped insert
provided in and at least substantially filling said chamber, one of
said housing and said insert having an elongated groove and the
other of said housing and said insert having a follower extending
into said groove.
18. The gearing of claim 17, wherein said groove is provided in
said insert, said follower including a first portion mounted in
said housing and a second portion extending into said groove.
19. The gearing of claim 17, wherein said chamber has first and
second end portions spaced apart from each other in a
circumferential direction of said internal gear, said housing
having an inlet communicating with one end portion and an outlet
communicating with the other end portion of said chamber.
20. The gearing of claim 17, wherein said insert comprises at least
two discrete fillers.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to improvements in gearings in
general, and more particularly to improvements in gearings of the
type wherein an internal gear surrounds a second gear having an
annulus of external gear teeth in mesh with the annulus of gear
teeth forming part of the internal gear. Gearings of the type to
which the present invention pertains are often utilized in pumps,
e.g., in so-called internal gear pumps which serve to supply a
lubricant (such as oil) to various constituents of the power train
in a motor vehicle.
[0002] Published German patent application Serial No. 199 23 851
discloses a gearing wherein a housing confines a rotary internal
gear mating with a pinion which is installed within the internal
gear and defines therewith a relatively large crescent-shaped
chamber. The pinion receives torque from a prime mover (e.g., from
the engine of a motor vehicle) by way of a shaft, such as a
transmission shaft, and causes the internal gear to rotate about an
axis which is parallel to the rotational axis of the pinion. One
end of the crescent-shaped chamber communicates with an inlet
(e.g., a port provided in the housing) for admission of a hydraulic
fluid, and the other end of such chamber communicates with an
outlet provided in the housing to receive a flow or stream of fluid
which is pressurized on its way through the chamber.
[0003] A drawback of many presently known gearings of the above
outlined character is that the flow of fluid through the
crescent-shaped chamber is rather turbulent with attendant
undesirable effect upon the characteristics of the body of fluid
(such as lubricant) which is being conveyed into and beyond the
outlet of the housing. For example, eddy currents developing in the
body of liquid flowing through the crescent-shaped chamber can
cause an overheating of a modern internal gear pump with attendant
problems involving adequate cooling of the pressurized fluid and/or
of the mechanical parts of the power train in a motor vehicle.
[0004] Internal gear pumps of the above outlined character are
described and illustrated, for example, on pages 492-493 of "Modern
Automotive Technology" authored by James E. Duffy and published in
1994 by The Goodheart-Willcox Company, Inc., Tinley Park, Ill. The
gear pump which is described in this publication comprises an oil
pump body or housing which confines a driven (internal) gear and a
drive gear (pinion) which mates with the driven gear and receives
torque from a so-called drive spline. The latter can receive torque
from or can form part of the distributor, the crankshaft or an
accessory shaft and mates with a driven spline in the drive gear.
Lubricant (oil) at the inlet side of the pump is caught in the gear
teeth and is carried around the outer wall inside the pump housing.
When the lubricant reaches the outlet side of the pump, the gear
teeth mesh and seal. Lubricant caught in each gear tooth is forced
into the pocket at the pump outlet and pressure is formed. This
causes the lubricant to squirt out of the pump and to the engine
bearings and/or to other component parts which necessitate
reliable, thorough, frequent or continuous lubrication. Such
principle underlies the operation of a gear oil pump as well as
that of an internal gear oil pump.
[0005] As utilized in this specification and in the appended
claims, the term "spur gear" is intended to denote a gear (such as
a pinion) having an annulus of external teeth regardless of the
exact configuration and/or orientation of the teeth (i.e.,
(helical) teeth set obliquely to the axis of rotation, radial teeth
parallel to the axis of the wheel, or others).
[0006] The disclosure of the commonly owned German priority
application Serial No. 199 59 215.2 (filed Dec. 8, 1999), as well
as the disclosure of each United States and foreign patent and/or
patent application identified in the specification of the present
application, is incorporated herein by reference.
[0007] Commonly owned U.S. Pat. No. 5,667,448 (granted Sep. 16,
1997 to Oswald Friedmann for "POWER TRAIN") discloses certain
features of a power train which can employ an internal gear pump
for a suitable lubricant, such as oil.
OBJECTS OF THE INVENTION
[0008] An object of the present invention is to provide a novel and
improved gearing of the type wherein a housing confines an internal
gear and a spur gear mating with the internal gear.
[0009] Another object of the invention is to provide a novel and
improved internal gear pump which can be utilized with advantage in
the power trains of motor vehicles.
[0010] A further object of the instant invention is to provide a
novel and improved method of influencing the flow of a hydraulic
fluid (such as oil) through the crescent-shaped chamber of an
internal gear pump.
[0011] An additional object of the invention is to provide a novel
and improved method of enhancing the performance of an internal
gear pump which can be utilized with advantage in the lubricating
systems of power trains in motor vehicles.
[0012] Still another object of the invention is to provide a
gearing of the type wherein an internal gear and a spur gear mate
in a housing and define a crescent-shaped chamber, particularly for
compression of a hydraulic fluid entering at one end of the chamber
and exiting at the other end.
[0013] A further object of the invention is to provide novel and
improved means for preventing or greatly reducing turbulence in the
sickle-shaped chamber between an internal gear and a spur gear in
the housing of an internal gear pump, especially for use in the
power trains of motor vehicles.
[0014] Another object of the invention is to provide novel and
improved inserts for use in the sickle-shaped chambers of gearings
employing mating internal gears and spur gears.
[0015] An additional object of the invention is to provide a
gearing which constitutes an improvement over and a further
development of gearings disclosed in the aforementioned published
German patent application Serial No. 199 23 851 as well as in
published German patent applications Serial Nos. 37 23 557 A1 and
43 22 239 A1.
[0016] Still another object of the invention is to provide an
internal gear pump which constitutes an improvement over and a
further development of pumps of the type disclosed in the
aforementioned published German patent applications.
SUMMARY OF THE INVENTION
[0017] One feature of the present invention resides in the
provision of a gearing which comprises a housing, an internal gear
which is rotatably mounted in the housing, and a spur gear which is
rotatably mounted in the housing, which mates with the internal
gear and which defines with the internal gear a substantially
crescent-shaped chamber. The improved gearing further comprises an
engine- or motor-driven shaft or other suitable means for rotating
one of the gears to thus rotate the other gear, and an insert which
is provided in and at least substantially fills the chamber. The
insert includes a first filler, at least one abutment for the first
filler, and a second filler.
[0018] The at least one abutment is or can be disposed between the
first and second fillers, as seen in the circumferential direction
of the internal gear.
[0019] At least one of the fillers has or can have an outline
resembling a portion of the outline of the substantially
crescent-shaped chamber. Such at least one filler can occupy
approximately one-half of the chamber. For example, each of the
fillers can have an outline resembling that of a portion of the
substantially crescent-shaped chamber, and each filler can occupy
approximately one-half of the chamber.
[0020] At least one of the fillers can comprise a plurality of
(e.g., two) discrete sections. The arrangement can be such that the
insert comprises only two fillers, that one of the fillers is a
one-piece component, and that the other filler comprises a
plurality of sections.
[0021] The housing can be provided with a fluid-admitting inlet
which communicates with one end portion of the chamber and with a
fluid-evacuating outlet which communicates with the other end
portion of the chamber. The two end portions of the chamber are
spaced apart from each other as seen in the circumferential
direction of the internal gear. One of the fillers of the insert
can be installed in the chamber adjacent the inlet, and the other
filler of the insert can be installed in the chamber adjacent the
outlet. The at least one abutment is or can be rigid with the
housing and can be disposed intermediate the one filler and the
other filler, as seen in the circumferential direction of the
internal gear.
[0022] The housing can form part of an internal gear pump.
[0023] In many or most instances, the engine- or motor driven gear
is the spur gear.
[0024] One of the fillers can comprise discrete first and second
sections and at least one sealing element between the first and
second sections.
[0025] The means for rotating the one gear can comprise a
power-driven drive spline and a complementary internal spline
provided in the spur gear and meshing with the drive spline.
[0026] Certain teeth of the internal gear mate with the adjacent
teeth of the spur gear in a region which is adjacent the inlet
and/or the outlet of the chamber, for example, in a region located
between the inlet and the outlet and opposite the chamber.
[0027] Another feature of the invention resides in the provision of
a gearing which comprises a housing, an internal gear which is
rotatably mounted in the housing, and a spur gear which is
rotatably mounted in the housing, which mates with the internal
gear and which defines with the internal gear a substantially
crescent-shaped chamber. The improved gearing further comprises
means for rotating one of the gears to thus rotate the other gear
by way of the one gear, and a substantially crescent-shaped insert
which is provided in and at least substatially fills the chamber.
The insert or the housing has an elongated groove, and the housing
or the insert has a follower which extends into the groove.
[0028] The groove can be provided in the insert and the follower
then includes a first portion which is rigid with or is rotatably
or turnably mounted in the housing and a second portion which
extends into the groove.
[0029] The chamber has first and second end portions which are
spaced apart from each other as seen in the circumferential
direction of the internal gear, and the housing is or can be
provided with an inlet in communication with one end portion and an
outlet in communication with the other end portion of the
chamber.
[0030] The insert can comprise at least two discrete fillers.
[0031] The novel features which are considered as characteristic of
the invention are set forth in particular in the appended claims.
The improved gearing itself, however, both as to its construction
and the modes of assembling and utilizing the same, together with
numerous additional important and advantageous features and
attributes thereof, will be best understood upon perusal of the
following detailed description of certain presently preferred
specific embodiments with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is an axial sectional view of an internal gear oil
pump which can be utilized to convey pressurized oil or another
suitable lubricant into the case of a transmission in the power
train of a motor vehicle;
[0033] FIG. 2 is a front elevational view of certain parts of a
gearing which is installed in the pump of FIG. 1 and wherein a
crescent-shaped chamber which is defined by an internal gear and a
spur gear is substantially filled by a composite insert including a
one-piece filler, a two-piece filler and an abutment between the
fillers;
[0034] FIG. 3 is a similar front elevational view of certain parts
of a modified gearing wherein the crescent-shaped chamber contains
an insert including a one-piece filler, a two-piece filler and a
projection having a follower extending into a groove of one of the
fillers; and
[0035] FIG. 3a is a fragmentary sectional view substantially as
seen in the direction of arrows from the line IIIa-IIIa of FIG.
3.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0036] FIG. 1 illustrates certain details of a gearing 1 which is
embodied in an internal gear oil pump. The gearing 1 comprises a
housing 5 having a bore or compartment 4 for a rotary internal gear
2 and a rotary spur gear 3 which is surrounded by the gear 2 and
has an annulus of external gear teeth some of which mate with the
adjacent internal teeth of the gear 2. The gear 3 is rotatable
about the axis of a tubular bearing member 6 which is installed in
the housing 5. The bearing member 6 surrounds a shaft 7, e.g., a
transmission shaft in the power train of a motor vehicle. The shaft
7 carries a connector 8 which cannot rotate relative to the shaft.
This connector is a ring acting as a drive spline which rotates
with the shaft 7 and is non-rotatably coupled to the gear 3. Thus,
when the shaft 7 receives torque from a prime mover (such as the
internal combustion engine, not shown, of a motor vehicle), it
indirectly rotates the internal gear 2 clockwise by rotating the
gear 3 anticlockwise, or vice versa.
[0037] The ring-shaped connector (drive spline) 8 has one or more
(e.g., three equidistant) internal projections 8a in the form of
teeth or the like which extend into complementary splines or tooth
spaces 9 of the shaft 7 to thus establish a torque-transmitting
connection between the parts 7 and 8. The connector 8 is further
provided with external teeth or analogous projections 8b extending
into complementary tooth spaces 10 in the interior of the gear 3.
Thus, the connector 8 can be said to constitute a power-driven
drive spline and the radially innermost portion of the gear 3 can
be said to constitute a complementary internal spline meshing (at
10) with the drive spline to receive torque from the shaft 7 and to
transmit torque to the internal gear 2. The connector 8 can be
provided with a single external projection 8b or with two or more
(e.g., three) equidistant projections 8b which extend into the
tooth spaces 10 of the gear 3.
[0038] The gear 3 surrounds a bearing 11 (e.g., a simple
sleeve-like friction bearing or slide bearing, or a standard
antifriction roller bearing) which, in turn, surrounds the
sleeve-like bearing member 6. The latter is non-rotatably mounted
in the housing 5. The bearing 11 can be a simple antifriction
roller bearing with balls or other suitable rolling elements
directly contacting the external surface of the bearing member 6.
If the bearing 11 is a ball or roller or needle type bearing and
the member 6 constitutes the inner race of such bearing, this
member is preferably hardened in accordance with any suitable
technique.
[0039] A further bearing 12 (such as a sleeve-like or roller
bearing) is installed between the internal surface of the member 6
and the external surface of the shaft 7. If the bearing 12
comprises a set of spherical or otherwise configurated (such as
needle-like) rolling elements, the shaft 7 can constitute the inner
race and the member 6 can constitute the outer race of such
bearing. FIG. 1 shows that the bearing 12 (preferably an
antifriction roller or needle bearing) is received in an external
groove 7b of the shaft 7.
[0040] In the embodiment of FIG. 1, the bearing 12 is installed in
the groove 7b adjacent the surface at the bottom of the compartment
4 in the housing 5. However, it is also possible to install the
bearing 12 within the confines of the internal gear 2. In the
illustrated axial position, the bearing 12 can take up radially
inwardly oriented stresses which would tend to subject the
sleeve-like bearing member 6 to deforming stresses, at least to
dynamic deforming stresses. Instead of transmission of such radial
stresses to the bearing member 6, the bearing 12 can transmit these
stresses to the much sturdier shaft 7 which can readily withstand
pronounced dynamic and/or other stresses developing and acting
radially inwardly when the gearing 1 is in use.
[0041] Another advantage of the gearing 1 is that it need not
employ an additional power input member, i.e., an additional drive
shaft. The shaft 7 can perform such function in addition to its
function as part of the transmission. In many instances, the shaft
7 can be journalled in such a way that it does not require any
additional bearing or bearings in the region of the pump, i.e.,
adjacent the gears 2 and 3. In FIG. 1, the bearing for the, shaft 7
merely includes the sleeve-like member 6 and the aforediscussed
friction or antifriction bearing 12.
[0042] The bearing 12 is lubricated by a suitable fluid (such as
oil) which fills a plenum chamber 13 of the transmission including
the shaft 7. To this end, a sealing ring 14 which is recessed into
the circumferential groove of the shaft 7 within the sleevelike
bearing member 6 is dimensioned, configurated and installed in such
a way that it allows lubricant to flow from the plenum chamber 13
to the bearing 12. In fact, the sealing ring 14 is installed
outside of the shortest path for direct flow of lubricant from the
plenum chamber 13 to the bearing 12, i.e., the ring 14 is installed
to the right of the chamber 13 and the bearing 12 as seen in FIG.
1. The ring 14 is in sealing engagement with the adjacent portion
of the internal surface of the sleeve-like bearing member 6 and in
sealing engagement with the surface bounding the groove in the
external surface of the shaft 7 so that it prevents escape of
lubricant toward the connector 8.
[0043] A corrugated annular seal 15 (or another suitable
ring-shaped sealing element) establishes a reliable sealing action
between the shaft 7 and the adjacent portion of the transmission
case 40.
[0044] The housing 5 is preferably a composite housing which, in
the embodiment of FIG. 1, comprises two plates or walls 20, 21 and
a central part 5a. The latter defines the compartment 4 which
confines the gears 2 and 3. The compartment 4 is sealed from the
surrounding area save for the provision of a fluid-admitting inlet
22 and a fluid-evacuating outlet 23. The transmission case 40 has a
first channel 24 for admission of fluid into the compartment 4 via
inlet 22, and a second channel 25 for evacuation of pressurized
fluid from the compartment 4 via outlet 23.
[0045] The plate 20 of the housing 5 is received in a recess 90 of
the transmission case 40 and is adjacent the right-hand end face of
the main portion 5a of the housing. The transmission case 40 can be
provided with a lid (not shown) which can be opened to afford
access to the plate 20. Such arrangement enables the plate 20 of
the housing 5 of the gearing 1 to reinforce the transmission case
40 in the region of the gearing. The housing 5 is affixed to the
transmission case 40 by suitable fasteners, e.g., by threaded
fasteners which are omitted in FIG. 1 for the sake of clarity. The
illustrated mounting of the housing 5 on the transmission case 40
exhibits the advantage that it occupies a small amount of space (as
seen in the axial direction of the gears 2 and 3) and that it can
stand pronounced axial and other stresses.
[0046] The plates 20, 21 are anchored in the main portion 5a of the
housing 5 by at least two parallel pins or studs 91 and 92. It is
also possible to anchor the plates 20, 21 in the transmission case
40 by means of pins or analogous parts in addition to or in lieu of
the anchoring pins 91, 92. Such pins extend into suitable blind
bores or holes provided in the plates 20, 21 and in the
transmission case 40 and/or main housing portion 5a. The purpose of
such anchoring means is to prevent (or to greatly reduce the
likelihood of) undesirable stray movements of the parts 5a, 20, 21,
40 relative to each other, for example, to hold the plates 20, 21
against friction-induced angular movements in their respective
planes and/or against axial movements toward and/or away from each
other.
[0047] It is often advisable to fix at least one of the plates 20,
21 against axial movement relative to the gears 2, 3, e.g., in the
region of an entraining element and an abutment or stop.
[0048] As already mentioned hereinbefore, the housing 5 of the
gearing 1 is secured to the transmission case 40 by means of
suitable threaded fasteners or the like, not shown. Such fasteners
can extend through bores or holes (not shown) in the housing 5 and
into tapped bores or holes in the transmission case 40. This mode
of securing the housing 5 to the transmission case 40 is preferred
at this time because the through bores or holes and the tapped
bores or holes need not be sealed to prevent escape of fluid from
the compartment 4 into the atmosphere or the inflow of air into the
compartment 4.
[0049] It is further advisable to adequately seal the bore 4 from
the atmosphere by one or more sealing elements (one shown at 41)
interposed between the housing 5 and the transmission case 40.
[0050] The shaft 7 is or can constitute the input shaft of the
transmission. The reason is that the RPM of the input shaft
normally exceeds that of the output shaft. The illustrated shaft 7
has external teeth 7a which receive torque from a gear or belt or
chain (not shown) driven by a prime mover.
[0051] The structure shown in FIG. 1 is identical with that shown
in FIG. 1 of the aforementioned published German patent application
Serial No. 199 23 851 A1.
[0052] FIG. 2 illustrates certain details of the gearing 100 which
embodies one presently preferred form of the instant invention. The
gearing 100 includes the housing 5 of FIG. 1 for the rotary
internal gear 2 and the spur gear 3 which mates with and is
surrounded by the internal gear. The spur gear 3 is driven by the
shaft 7 (not shown in FIG. 2) in a manner as described in
connection with FIG. 1. Some of the external gear teeth 3a of the
spur gear 3 mate with the adjacent internal gear teeth 2a of the
gear 2 in the region of the inlet 22 provided in the housing 5 for
the admission of fluid into the adjacent end portion of a
crescent-shaped chamber 110 defined by the gears 2, 3 in the region
where their gear teeth 2a, 3a are out of mesh or in partial mesh
with each other. The other end portion of the chamber 110
communicates with the outlet 23 of the housing 5.
[0053] In accordance with a feature of the invention, that portion
of the chamber 110 which extends between the inlet 22 and the
outlet 23 is at least substantially completely occupied by a
composite crescent-shaped insert including a first filler 140 and a
second filler 150. Each of these fillers takes up approximately
one-half of the chamber 110 and its shape conforms to or resembles
the outline of the respective half of the chamber, i.e., each of
the fillers can be said to resemble one-half of a crescent or
sickle having an outline corresponding to that of the chamber 110
between the inlet 22 and the outlet 23.
[0054] The filler 140 is of one piece (i.e., a single piece of a
suitable metallic or plastic material) and is secured to the
housing 5 by means of suitable fasteners 141, 142 (e.g., by
threaded fasteners). This filler is adjacent the inlet 22. The
other filler 150 comprises two sections or parts 151, 152 and is
adjacent the outlet 23. The section 152 has a groove or recess for
a sealing element 153 which engages the section 151. The purpose of
this sealing element is the same as that of the sealing element
shown in FIG. 3 of the German patent application Serial No. 199 23
851 and of sealing elements shown in FIGS. 2 and 3 of published
German patent application Serial No. 43 22 239 A1. Each of these
German patent applications discloses and shows an insert which
occupies only one-half of the crescent-shaped chamber.
[0055] The insert including the fillers 140, 150 further comprises
an abutment 160 which has end portions recessed in blind bores or
holes of the plates or walls 20, 21 and serves as a stop for the
sections 151, 152 of the composite filler 150. The other filler 140
has a concave end face 143 adjacent a complementary convex surface
of the abutment 160.
[0056] The advantage of the insert including the fillers 140, 150
and the abutment 160 is that they effectively prevent eddying
and/or other forms of undesirable turbulence in the stream of
hydraulic fluid flowing from the inlet 22 through the unoccupied
portion of the chamber 120 and the adjacent tooth spaces between
the teeth 2a as well as between the teeth 3a. Such absence of
turbulence is highly desirable for a number of important reasons
such as preventing overheating of the conveyed fluid and of the
pump, more predictable flow of fluid from the inlet 22 to the
outlet 23 and greater predictability of pressurization of fluid on
the way from the inlet 22 to the outlet 23 of the housing 5.
[0057] FIG. 3 illustrates certain novel features of a modified
gearing 200 having a housing 205 (FIG. 3a) corresponding to the
housing 5 of FIG. 1, an internal gear 201 rotatably mounted in the
housing 205, and a spur gear 202 mating with the internal gear 201.
The gear 202 is driven by a shaft (such as the shaft 7 shown in
FIG. 1) and rotates the gear 201 when the gearing 200 is in use.
The gears 201, 202 define a crescent-shaped chamber 210 one end
portion of which communicates with the inlet 220 and the other of
which communicates with the outlet 230 of the housing 205. The
teeth 201a of the internal gear 201 mate with the teeth 202a of the
spur gear 202 in the region opposite the chamber 210.
[0058] A major part well in excess of one-half of the chamber 210
is filled by a composite sickle- or crescent-shaped insert 250
including two crescent-shaped fillers 251, 252. The inner filler
252 has an axially parallel groove for a sealing element 253 which
bears against the adjacent concave side of the outer filler 251.
When the gearing 200 is in use, i.e., when the gear 202 drives the
gear 201 so that a hydraulic fluid is pressurized on its way
through the chamber 210 in a direction from the inlet 220 toward
the outlet 230, the insert 250 is urged against a projection 260
which is rotatably mounted in the housing 205 and has a follower
261 extending into a groove 255 of the insert 250. The follower 261
has a substantially rectangular outline (see FIG. 3) and the insert
250 is movable relative to the housing 205.
[0059] The insert 250 fills the chamber 210 to such an extent that
the turbulence in the stream of fluid flowing in the chamber 210
from the inlet 220 to the outlet 230 is nil or negligible.
[0060] The manner in which the projection 260 is mounted in the
housing 205 (e.g., between two plates or walls corresponding to the
plates 20, 21 shown in FIG. 1) is or can be the same as shown in
FIG. 2 or 3 of published German patent application Serial No. 37 23
557 A1.
[0061] The exact nature of the material of which the insert of FIG.
2 or the insert of FIGS. 3 and 3a is made depends upon a variety of
factors such as the purpose of the gearing, the range of pressures
to which the fluid is subjected on its way from the inlet to the
outlet of the housing, and the quantity of fluid being conveyed per
unit of time. In many instances, the insert will be made of a
metallic or a plastic material.
[0062] Without further analysis, the foregoing will so fully reveal
the gist of the present invention that others can, by applying
current knowledge, readily adapt it for various applications
without omitting features that, from the standpoint of prior art,
fairly constitute essential characteristics of the generic and
specific aspects of the above outlined contribution to the art and,
therefore, such adaptations should and are intended to be
comprehended within the meaning and range of equivalence of the
appended claims.
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