U.S. patent application number 13/130219 was filed with the patent office on 2011-09-15 for fuel pump for internal combustion engines.
This patent application is currently assigned to THIELERT AIRCRAFT ENGINES GMBH. Invention is credited to Carsten Rudolph.
Application Number | 20110223049 13/130219 |
Document ID | / |
Family ID | 42114315 |
Filed Date | 2011-09-15 |
United States Patent
Application |
20110223049 |
Kind Code |
A1 |
Rudolph; Carsten |
September 15, 2011 |
Fuel Pump For Internal Combustion Engines
Abstract
A fuel pump is disclosed, especially a prefeed pump for feeding
aircraft fuel to the high pressure pump, wherein the form-fit
connection between the drive shaft (4) and the driven impeller (2)
is produced by a regular, convex, triangular polygonal contour
having rounded-off lateral faces and corner faces, the drive shaft
and the impeller being provided with the polygonal contour. In this
manner, the wear resulting from the poor lubricating power of the
kerosene-based aircraft fuel can be reduced and the service life of
the fuel pump can be increased.
Inventors: |
Rudolph; Carsten;
(Bendestorf, DE) |
Assignee: |
THIELERT AIRCRAFT ENGINES
GMBH
Lichtenstein
DE
|
Family ID: |
42114315 |
Appl. No.: |
13/130219 |
Filed: |
November 13, 2009 |
PCT Filed: |
November 13, 2009 |
PCT NO: |
PCT/EP2009/065180 |
371 Date: |
May 19, 2011 |
Current U.S.
Class: |
418/102 ;
418/206.8 |
Current CPC
Class: |
F04C 2240/20 20130101;
F16D 2001/102 20130101; F04C 15/0076 20130101; F04C 15/0073
20130101; F16D 1/101 20130101; F04C 2/18 20130101; F02M 37/04
20130101; F04C 2240/60 20130101 |
Class at
Publication: |
418/102 ;
418/206.8 |
International
Class: |
F04C 2/18 20060101
F04C002/18; F04C 15/00 20060101 F04C015/00; F04C 29/02 20060101
F04C029/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 21, 2008 |
DE |
10 2008 043 991.6 |
Claims
1. A fuel prefeed pump for supplying fuel to a high pressure fuel
pump for supplying diesel engines operated with aircraft fuel
comprising a gear pump having a pump gear driven via a driveshaft,
a form-fit connection between the driven pump gear (2) and the
driveshaft (4) embodied as a regular convex polygon having lateral
faces and corner regions curved to an outside thereof.
2. The fuel prefeed pump according to claim 1, characterized in
that the form-fit polygon connection comprises a coupling disc (5)
provided on the driveshaft (4) and a recess (6) moulded into the
driven pump gear (2) having the corresponding polygonal
contour.
3. The fuel prefeed pump according to claim 1, characterized in
that the convex polygonal contour is triangular and in a radius
R.sub.S has lateral faces curved to the outside and in a radius
R.sub.E has corner regions curved to the outside.
4. The fuel prefeed pump according to claim 1, characterized in
that the regular convex polygonal contour is a tetragon contour or
a pentagon contour.
5. The fuel prefeed pump according to claim 2, characterized in
that the convex polygonal contour is triangular and in a radius
R.sub.S has lateral faces curved to the outside and in a radius
R.sub.E has corner regions curved to the outside.
6. The fuel pump according to claim 2, characterized in that the
regular convex polygonal contour is a tetragon contour or a
pentagon contour.
Description
TECHNICAL FIELD
[0001] The invention relates to a fuel pump, especially a prefeed
pump for internal combustion engines comprising a gear pump with a
pump impeller driven via a driveshaft, more preferably for diesel
engines operated with aircraft fuel.
BACKGROUND
[0002] The fuel feed to the combustion chamber of aircraft engines
operated in common-rail technology using aircraft fuel takes place
from a tank via a prefeed pump and a high-pressure pump to a common
distribution pipe (rail) connected to the individual cylinders, as
is well known. Since a failure of a fuel pump invariably results in
engine stoppage, an extremely high reliability is demanded
particularly with aircraft engines. The reliability and the maximum
operating duration of the fuel pumps are particularly limited in
that they are lubricated with the delivered fuel and the bearings
and sliding surfaces are under more or less load corresponding to
the lubricating power of the fuel. The lifespan of the fuel pumps
is thus decisively influenced by the lubricating properties of the
respective fuel. Since the diesel engines employed in aircraft are
operated with a kerosene-based aircraft fuel with significantly
lower lubricating power compared with diesel fuel, the lifespan of
the fuel pumps in this case is particularly low.
[0003] In the case of a prefeed pump designed as a gear pump the
pump gear (drive gear) of said prefeed pump is connected to a drive
shaft by way of a splined shaft toothing, whose outer toothing
(outer profile) present on a shaft end form-fittingly engages in an
internal toothing (inner profile) present on the drive gear of the
prefeed pump. The prefeed pump designed in this manner only has a
very short lifespan when used for a diesel engine operated with
aircraft fuel since the driveshaft and the driven pump gear and
consequently also the pump housing are subjected to high wear and
the prefeed pump has to be replaced completely even after a short
operating time.
[0004] DE 100 14 548 A1 describes a gear feed pump for diesel fuel
with which the form-fit connection between the drive shaft and the
one pump gear is established through a flattened circle geometry or
via a profiling provided with recesses and protrusions.
SUMMARY OF THE INVENTION
[0005] The invention is therefore based on the object of designing
the prefeed pump connected upstream of the high-pressure pump in
such a manner that even when using fuel with reduced lubricating
power a long lifespan is guaranteed.
[0006] According to the invention, this object is solved with a
fuel pump or prefeed pump designed as gear pump, specifically a
fuel pump, particularly a prefeed pump for internal combustion
engines comprising a gear pump with a pump gear driven via a
driveshaft, more preferably for diesel engines operated with
aircraft fuel, characterized by a form-fit connection embodied as a
regular convex polygon having lateral faces and corner regions
curved to the outside between the driven pump gear and the
driveshaft. Practical configurations of the invention are discussed
below.
[0007] The essence of the invention in other words consists in that
the form-fit connection between the driveshaft and the driven pump
gear is established through a convex polygonal contour designed on
the driveshaft and on the pump gear.
[0008] In a further embodiment of the invention the driveshaft
comprises a coupling disc in the shape of a polygon shaped as
triangle with lateral faces curved outwardly at a certain radius
and corner regions rounded towards the outside, while in the driven
pump gear a recess corresponding in shape and size to the coupling
disc is formed, so that the coupling disc engages in the recess as
an accurate fit.
[0009] Surprisingly it was discovered that the connection between
driveshaft and pump gear established via two polygons
form-fittingly engaging into each other guarantees a secure power
transmission and results in a significant reduction of the wear on
the form-fit connection point and thus the driveshaft, the pump
gears and the pump housing and thus the lifespan of the fuel pump
provided for delivering fuel with low lubricating power is
increased and its especially for aviation indispensable reliability
is improved. In a further configuration of the inventions the
convexly curved polygonal contours form-fittingly engaging into
each other can also be embodied as polygon, for example as
tetragon.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] An exemplary embodiment of the invention is explained in
more detail by means of the drawing. It shows:
[0011] FIG. 1 a perspective representation of a prefeed pump
designed as gear pump in a disassembled state;
[0012] FIG. 2 a front view of the driveshaft designed with a
coupling disc designed as polygon; and
[0013] FIG. 3 a front view of the drive gear of the prefeed pump
with an inner profile designed as polygon.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The prefeed pump shown in a disassembled state in FIG. 1 is
designed as gear pump and comprises a pump housing 1, in which a
driven first pump gear 2 and a second pump gear 3 are mounted. In
addition, a driven driveshaft 4 is mounted in the pump housing 1. A
coupling disc 5 moulded onto the driveshaft 4 has the shape of a
convex, regular, in this case, triangular polygon, i.e. of a
triangle with three curved lateral faces of the same length and the
same size internal angles. The coupling disc 5 engages in a recess
6 formed in the driven pump gear 2 whose contour shaped as polygon
corresponds to the contour of the coupling disc 5. Subject to the
intermediate connection of a sealing ring 8 the pump housing 1 is
closed-off through a housing cover 9 which is fastened by means of
cheese-head screws.
[0015] The polygonal outer contour of the coupling disc 5 and the
recess 6 provided in the driven pump gear 2 is shown in more detail
in the FIGS. 2 and 3. The regular triangular polygon of the
coupling disc 5 and of the recess 6 has a circumcircle with the
diameter d.sub.U and an incircle with the diameter d.sub.I.
However, the polygon has no straight lateral edges (lateral faces)
but is convexly shaped, i.e. with crowned lateral faces curved
outwardly in the radius R.sub.S and within the radius R.sub.E
rounded corner regions of the polygon of the coupling disc 5 and of
the recess 6. The maximum width of the polygon of the recess 6 or
of the coupling disc 5 is designated W in the drawing.
[0016] With the form-fit between the driveshaft 6 and the driven
pump gear embodied as convex polygonal connection the wear of the
first and also of the second pump gear as well as of the driveshaft
and of the housing can be significantly lowered and the lifespan of
the prefeed pump designed as gear pump can be increased by up to
three times even when using a fuel with low lubricating power.
[0017] The invention is not restricted to the exemplary embodiment
described before. For example, the form-fit connection can also be
formed through regular convex polygons with more than three corners
such as a tetragon or pentagon and also be employed with other fuel
pumps with rotating pump wheels.
LIST OF REFERENCE CHARACTERS
[0018] 1. Pump housing
[0019] 2. First, driven pump gear
[0020] 3. Second pump gear
[0021] 4. Driveshaft
[0022] 5. Coupling disc, triangular convex polygon
[0023] 6. Recess, triangular convex polygon
[0024] 7. Cheese-head screws
[0025] 8. Sealing ring
[0026] 9. Housing cover
[0027] D.sub.U Circumcircle of polygon
[0028] D.sub.I Incircle of polygon
[0029] W Maximum width of the polygon
[0030] R.sub.S Radius of the lateral faces of the polygon
[0031] R.sub.E Radius of the corner faces of the polygon
* * * * *