U.S. patent application number 10/856792 was filed with the patent office on 2004-12-09 for fuel supply apparatus.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Suzuki, Masashi.
Application Number | 20040247464 10/856792 |
Document ID | / |
Family ID | 33161584 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040247464 |
Kind Code |
A1 |
Suzuki, Masashi |
December 9, 2004 |
Fuel supply apparatus
Abstract
A fuel feed pump according to the present invention improves its
pump performance by making smaller side clearances in an axial
direction at both sides of a pump element PE. Multiple
through-holes passing through in an axial direction are
respectively formed at top portions of cogs of the outer rotor and
the inner rotor, which form a pump element of a feed pump.
Accordingly, pressures in the thrust direction at both axial sides
of the rotors can be equalized, since the side clearance formed at
both axial sides of the rotors are communicated with each other. As
a result, since the rotors can be floated, without contacting with
the pump cover and the pump plate, the abnormal wear and seizures
can be suppressed, even when side clearance between the pump cover
and the pump element is made smaller.
Inventors: |
Suzuki, Masashi; (Obu-city,
JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
1100 N GLEBE ROAD
8TH FLOOR
ARLINGTON
VA
22201-4714
US
|
Assignee: |
DENSO CORPORATION
Aichi-pref
JP
|
Family ID: |
33161584 |
Appl. No.: |
10/856792 |
Filed: |
June 1, 2004 |
Current U.S.
Class: |
417/410.3 ;
417/410.4 |
Current CPC
Class: |
F04C 2230/602 20130101;
F04C 2/344 20130101; F04C 2/084 20130101; F04C 15/0042 20130101;
F04B 23/103 20130101; F04B 23/12 20130101; F04C 11/006 20130101;
F04C 2/102 20130101 |
Class at
Publication: |
417/410.3 ;
417/410.4 |
International
Class: |
F04B 017/00; F04B
039/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 4, 2003 |
JP |
2003-159280 |
Apr 21, 2004 |
JP |
2004-125490 |
Claims
What is claimed is:
1. A fuel supply apparatus comprising: a rotary pump having a rotor
and a pumping chamber, volume of the pumping chamber being varied
in conjunction with rotation of the rotor, and for pressurizing
fuel sucked into the pumping chamber and discharging the
pressurized fuel, wherein multiple through-holes are formed in the
rotor in its axial direction, and side clearances formed at both
sides of the rotor are communicated with each other though those
through-holes.
2. A fuel supply apparatus according to claim 1, wherein the
multiple through-holes are formed at an equal distance in a
circumferential direction of the rotor.
3. A fuel supply apparatus according to claim 1, wherein the rotary
pump is a trochoid type pump comprising an outer rotor having inner
cogs and an inner rotor disposed inside of the outer rotor and
having outer cogs, wherein the through-holes are formed at top
portions or bottom portions of the cogs.
4. A fuel supply apparatus according to claim 3, wherein the rotary
pump is provided with the through-holes at every top portion or
bottom portion of the cogs.
5. A fuel supply apparatus according to claim 3, wherein an outer
rotor of the rotary pump is provided with multiple through-holes,
which pass through in the axial direction, at top portions or
bottom portions of the cogs.
6. A fuel supply apparatus according to one of claim 3, wherein the
fuel supply apparatus is a fuel injection pump for a diesel engine
for which the rotary pump is used as a feed pump, wherein the feed
pump comprises: a circular rotor chamber; a pump cover for housing
a pump element of the inner and the outer rotors in the rotor
chamber; and a pump plate for closing an open end of the rotor
chamber in a liquid-sealing manner together with the pump cover,
wherein the pump plate is formed with fuel ports to be communicated
to the rotor chamber, and the pump cover is screwed to a side
surface of a housing of the fuel injection pump, so that the pump
plate is pressed against the side surface.
7. A fuel supply apparatus according to claim 1, wherein the rotary
pump is a vane type pump comprising a rotor formed with vane
grooves and vanes movably inserted into the vane grooves.
8. A fuel supply apparatus for an internal combustion engine
comprising: a main pump for supplying a high pressure fuel to the
engine; and a feed pump fixed to the main pump for feeding fuel
from a fuel tank to the main pump, wherein the feed pump including:
a pump housing forming a pumping chamber; and a pump rotor
operatively connected to the main pump and rotationally supported
in the pumping chamber, wherein multiple through-holes are formed
in the rotor so that side clearances between the pump housing and
both side surfaces of the rotor are communicated with each
other.
9. A fuel supply apparatus according to claim 8, wherein the
multiple through-holes are formed in the rotor at an equal distance
in a circumferential direction.
10. A fuel supply apparatus according to claim 8, wherein the feed
pump is of a trochoid type pump comprising: an outer rotor
rotationally supported in the pump housing and having inner cogs;
and an inner rotor disposed inside of the outer rotor and having
outer cogs, wherein the multiple through-holes are formed at the
respective cogs.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application
Nos. 2003-159280 filed on Jun. 4, 2003 and 2004-125490 filed on
Apr. 21, 2004, the disclosures of which are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] This invention relates to a fuel supply apparatus for an
internal combustion engine, more particularly to a rotary pump to
be used for a fuel injection system for supplying fuel to a diesel
engine.
BACKGROUND OF THE INVENTION
[0003] As one of prior art fuel injection pump, for example shown
in U.S. Patent Application Publication No. US 2003/0044288 A1, it
is known to us that the fuel injection pump is provided with a feed
pump for drawing fuel from a fuel tank and feeding the fuel to a
main pump of the fuel injection pump.
[0004] As shown in FIG. 6, the feed pump comprises a pump element
110 to be driven by a cam shaft 100 of a main pump, a pump cover
120 for forming a rotor chamber and housing therein the pump
element 110, and a pump plate 130 for closing an opening side of
the rotor chamber in a liquid-sealing manner in combination with
the pump cover 120, wherein the pump cover 120 is screwed to a side
surface of a pump housing 140.
[0005] Furthermore, as shown in FIG. 7, the pump element 110 is a
trochoid type comprising an outer rotor 111 having inner cogs and
an inner rotor 112 disposed inside of the outer rotor and having
outer cogs, wherein the number of cogs of the outer rotor 111 is
larger than that of the inner rotor 112 by one cog, and wherein a
rotational center 0a of the outer rotor 111 is eccentric from that
0i of the inner rotor 112. As a result, when the inner rotor 112 is
driven by the cam shaft 100 and rotated, the outer rotor 111 is
also rotated in conjunction with the inner rotor 112, so that a
volume of a working chamber formed by adjacent cogs will be
gradually changed to draw fuel from a fuel tank and pumps out the
fuel to the main pump.
[0006] In the above described feed pump, as shown in FIG. 6, a side
clearance between the pump cover 120 and the pump element 110 is
made smaller to minimize amount of fuel leakage and to increase a
fuel feed efficiency. If, however, the side clearance were made too
small, there would occur a problem of an abnormal wear, seizure or
the like, because variations of parts in manufacturing process may
not be absorbed.
SUMMARY OF THE INVENTION
[0007] The present invention is made in view of the above problems,
and it is an object of the present invention to provide a fuel
supply apparatus having a rotary pump which improves a pump
performance by making much smaller the side clearance in an axial
direction at both sides of the pump element without causing metal
contact between the pump element and the counterpart.
[0008] According to one of features of the present invention, a
fuel supply apparatus comprises a rotary pump having a pumping
chamber, the volume of which varies in conjunction with a rotation
of a rotor, pressurizing the fuel sucked into the pumping chamber
and discharging the pressurized fuel. The rotary pump is
characterized in that, multiple through-holes are formed in a
rotor, wherein the through-holes pass through in the rotor in an
axial direction, and side clearances formed at both sides of the
rotor are communicated with each other by those through-holes.
[0009] According to the above structure, pressures (thrust
pressures) on both sides of the rotor in the axial direction are
equalized, since the side clearances formed at both sides of the
rotor are communicated with each other through those multiple
through-holes formed in the rotor. As a result, uniform side
clearances on both sides of the rotor can be attained. In other
words, it has become possible to float the rotor. Accordingly, the
fuel feed efficiency can be increased by making much smaller the
side clearance formed at both sides of the rotor in its axial
direction, and the problems of the abnormal wear, seizures and the
like can be suppressed because metal contacts between the rotor
forming the side clearances and other parts can be suppressed.
[0010] According to another feature of the invention, the multiple
through-holes are formed at an equal distance in a circumferential
direction of the rotor.
[0011] According to such a structure, since the pressures (thrust
pressures) on both sides of the rotor are equalized through those
multiple through-holes at those points of the equal distance in the
circumferential direction of the rotor, uniform side clearances can
be obtained on both sides of the rotor at almost all
circumferential points of the rotor. Accordingly, the fuel feed
efficiency can be increased by making the side clearances much
smaller, and the problems of the abnormal wear, seizures and the
like can be suppressed because metal contacts between the rotor and
other parts can be suppressed.
[0012] According to a further feature of the invention, the rotary
pump is a trochoid type pump comprising an outer rotor having inner
cogs and inner rotor disposed inside of the outer rotor and having
outer cogs, wherein the through-holes are formed at top portions or
bottom portions of the cogs.
[0013] Because of the through-holes formed in the inner rotor,
which is driven by a camshaft, the inner rotor can be floated. As a
result, metal contacts between the inner rotor and other parts are
suppressed during the rotation of the inner rotor, and thereby the
problems of the abnormal wear, seizures and the like can be
suppressed.
[0014] According to still further feature of the invention, the
rotary pump is provided with the through-holes at every top portion
or bottom portion of the cogs.
[0015] In this case, the pressures in the thrust direction can be
equalized at every top portion or bottom portion of the cogs of the
inner rotor, the inner rotor can be much more surely floated to
suppress the metal contacts between the inner rotor and the other
parts.
[0016] According to a further feature of the invention, an outer
rotor of the rotary pump is provided with multiple through-holes,
which pass through in the axial direction, at top portions or
bottom portions of the cogs, wherein the multiple through-holes are
arranged at an equal distance in a circumferential direction of the
outer rotor.
[0017] Since the through-holes are formed in the outer rotor in
addition to the through-holes in the inner rotor, thrust pressures
to the outer rotor can be likewise equalized. As a result, the
outer rotor can be positively floated together with the inner
rotor.
[0018] According to a further feature of the present invention, the
rotary pump is used as a feed pump of a fuel injection pump for
diesel engines, wherein the feed pump is formed with a circular
rotor chamber and comprises a pump cover for housing the pump
element of the inner and the outer rotors in the rotor chamber, and
a pump plate for closing an open end of the rotor chamber in a
liquid-sealing manner together with the pump cover. The pump plate
is formed with fuel ports to be communicated to the rotor chamber,
and the pump cover is screwed to a side surface of a housing of the
fuel injection pump, so that the pump plate is pressed against the
side surface.
[0019] According to the above structure, the side clearance between
the pump element and the pump cover as well as the side clearance
between the pump element and the pump plate can be made smaller to
increase the fuel feed efficiency and thereby increase a pump
performance as the feed pump.
[0020] According to a further feature of the invention, the rotary
pump is a vane type pump comprising a rotor formed with vane
grooves and vanes movably inserted into the vane grooves.
[0021] In the vane type pump, since the rotor having vanes is
driven by a cam shaft and is rotated, the rotor can be floated by
equalizing thrust pressures with multiple through-holes formed in
the rotor. As a result, the metal contacts between the rotor and
the other parts can be suppressed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The above and other objects, features and advantages of the
present invention will become more apparent from the following
detailed description made with reference to the accompanying
drawings. In the drawings:
[0023] FIG. 1 is a cross-sectional view of a feed pump according to
a first embodiment of the present invention;
[0024] FIG. 2 is a front view of a pump element of the feed pump
shown in FIG. 1;
[0025] FIG. 3 is a cross-sectional view of a fuel injection pump to
which the feed pump of the present invention is applied;
[0026] FIG. 4 is a front view of a pump element according to a
second embodiment of the present invention;
[0027] FIG. 5 is a front view of a pump rotor according to a third
embodiment of the present invention;
[0028] FIG. 6 is a cross-sectional view of a prior art feed pump;
and
[0029] FIG. 7 is a front view of a pump element of the feed pump
shown in FIG. 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0030] The present invention will be explained below with reference
to the embodiments.
[0031] In the first embodiment, an embodiment is explained in which
a fuel supply apparatus of the invention is used in a fuel
injection pump of a common rail fuel injection system for diesel
engines.
[0032] FIG. 1 is a cross-sectional view of a feed pump, FIG. 2 is a
front view of a pump element, and FIG. 3 is a cross-sectional view
of a fuel injection pump.
[0033] As shown in FIG. 3, the fuel injection pump 1 is provided
with a main pump 2 for pressurizing and pumping out fuel and a feed
pump 3 (See FIG. 1) for drawing the fuel from a fuel tank (not
shown) and feeding the fuel to the main pump 2.
[0034] The main pump 2 comprises a cam shaft 4 to be rotated being
driven by a diesel engine (not shown), a pump housing 5 for
rotationally supporting the cam shaft 4, a plunger 7 being driven
by the cam shaft 4 for reciprocally moving in a cylinder 6, and so
on.
[0035] A cam 8 which has a circular cross-sectional configuration
is fixed to the cam shaft 4, wherein a rotational center thereof is
eccentric to that of the cam shaft. A cam ring 10 is rotationally
supported at an outer periphery of the cam 8 over a bush 9. A pair
of flat surfaces are formed in the cam ring 10, wherein the flat
surfaces are opposing to each other in a radial direction of the
cam 8.
[0036] A pair of cylinder heads 11 is assembled to the pump housing
5 in a liquid-sealing manner, wherein the cylinder heads 11 are
opposing to each other in the radial direction of the cam shaft
4.
[0037] The cylinder head 11 is formed with a cylinder 6, into which
the plunger 7 is inserted, a pump-out port 12 to be communicated
with the cylinder 6, and so on. A check valve 13 is assembled to
the cylinder head at an opposite side of the cylinder 6. A pipe
joint 15 is screwed into the cylinder head at an outlet side of the
pump-out port 12 for connecting to a fuel pipe 14.
[0038] The check valve 13 is disposed between a fuel passage (not
shown) to be communicated with a feed pump and the cylinder 6. The
check valve 13 will be opened during a suction stroke at which the
plunger 7 will be downwardly moved in the cylinder 6 (inwardly
moved), to introduce fuel fed from the feed pump 3 into the inside
of the cylinder 6, whereas the check valve 13 will be closed during
a pumping out stroke at which the plunger 7 will be upwardly moved
in the cylinder 6 (outwardly moved) so that the fuel introduced
into the cylinder 6 is prevented from flowing back to the feed pump
3.
[0039] The pump-out port 12 is formed with a small diameter port
and a large diameter port. A seat surface of a circular conic is
formed between the small and large diameter ports (See FIG. 3). A
ball valve 17 is disposed in the pump-out port 12 and is urged by a
spring 16 towards the seat surface, so that the small and large
diameter ports are blocked by this ball valve 17.
[0040] The ball valve 17 will be lifted from the seat surface when
a pressure of fuel, which is pressurized by the plunger 7 during
the pumping out stroke, becomes higher than the urging force of the
spring 16, and thereby the small and large diameter ports are
communicated with each other.
[0041] The plunger 7 has a plunger head 7a at its inner side end
and the plunger head 7a is urged by a spring 18 and pressed against
an outer surface (flat surface) of the cam ring 10. When the
rotation of the cam shaft 4 is transmitted to the cam ring 10 via
the cam 8, the cam ring 10 moves with an orbital motion along its
orbit which is displaced from the rotational center of the cam
shaft 4 by a certain distance, while the cam ring 10 is keeping its
orientation (The cam ring 10 is not rotated on its axis and on an
axis of the cam 8). As a result, the plunger 7 pressed against the
flat surface of the cam ring 10 is reciprocally moved in the
cylinder 6.
[0042] The feed pump 3 comprises a pump element PE, a pump cover 19
and a pump plate 20, as explained below. The feed pump 3 is fixed
to a side surface of the pump housing 5 by bolts 21, as shown in
FIG. 3.
[0043] The pump element PE is a well known trochoid type pump,
comprising an outer rotor 22 having inner cogs and an inner rotor
23 disposed inside of the outer rotor 22 and having outer cogs,
wherein the inner rotor is connected to the cam shaft 4 via a key
so that the inner rotor will be rotated by the cam shaft 4.
[0044] The outer rotor 22 has cogs, the number of which is larger
than that of the inner rotor 23 by one cog, and the rotational
center 0a of the outer rotor 22 is eccentrically displaced from the
rotational center 0i of the inner rotor 23 (See FIG. 2).
Accordingly, when the inner rotor 23 is rotated by the cam shaft 4,
the outer rotor 22 is rotated in conjunction with the inner rotor
23, so that the volume of working chambers formed by the cogs will
be changed to pump out the fuel drawn from the fuel tank to the
main pump 2.
[0045] As shown in FIG. 2, through-holes 22a and 23a, which pass
through the outer and inner rotors 22 and 23 in an axial direction,
are respectively formed in the outer rotor 22 and the inner rotor
23. There are provided with multiple through-holes 22a and 23a in
the outer and inner rotors 22 and 23, and those through-holes are
formed at an equal distance in a circumferential direction (more
exactly, at every cog top portion of the outer and inner rotors 22
and 23).
[0046] The pump cover 19 is formed with a circular rotor chamber
19a for housing therein the pump element PE, as shown in FIG. 1. An
inner diameter of the rotor chamber 19a is made slightly larger
than an outer diameter of the pump element PE (namely, an outer
diameter of the outer rotor 23), so that the outer rotor 23 may be
rotated therein. A width of the rotor chamber 19a is made slightly
larger than a width of the pump element PE (a thickness in a
longitudinal direction), so that side clearances of a certain
distance between the pump element PE and inner surfaces of the pump
chamber are kept.
[0047] The pump plate 20 is assembled to the pump cover 19 in a
liquid-sealing manner to close an opening of the rotor chamber 19a.
The pump plate 20 is formed with a center bore, through which the
cam shaft 4 passes, and fuel ports 20a (an inlet port and an outlet
port) around the center bore (See FIG. 1). The fuel ports 20a are
communicated to the working chambers 24 formed between the outer
rotor 22 and the inner rotor 23.
[0048] An operation of the above first embodiment will be
explained. In the above feed pump 3, the multiple through-holes 22a
and 23a are respectively formed in the outer and inner rotors 22
and 23 and furthermore those multiple through-holes 22a and 23a are
arranged at equal distance in the circumferential direction of the
rotors 22 and 23. Since the side clearances formed on the both
sides of the rotors 22 and 23 in the axial direction are
communicated with each other through those multiple through-holes
22a and 23a, the pressures in the thrust direction at the both
sides of the rotors 22 and 23 will be equalized. As a result,
uniform side clearances can be obtained at both sides of the rotors
22 and 23.
[0049] According to the above structure, the outer and inner rotors
22 and 23 can be floated without contacting with the pump cover 19
and the pump plate 20. In particular, since the through-holes 23a
are formed at every cog top portions of the inner rotor 23, which
correspond to an outer periphery of the inner rotor, an inclination
of the inner rotor 23 can be effectively suppressed and thereby the
uniform side clearances at both of the longitudinal sides along the
peripheries of the inner rotor 23 can be obtained.
[0050] Accordingly, the problems of the abnormal wear and seizures
and the like can be suppressed by preventing the metal contacts
between the pump element PE and the pump cover 19 and the pump
plate 20, to finally increase the performance of the feed pump 3,
even when the side clearances between the pump element PE and the
pump cover 19 are made smaller to increase the fuel feed
efficiency.
[0051] In the above first embodiment, the through-holes 22a and 23a
are formed in the both outer and inner rotors 22 and 23. It is,
however, possible to obtain a sufficient effect (suppress of the
abnormal wear and seizures, or the like), when the through-holes
23a are formed only in the inner rotor 23 which is directly driven
by the cam shaft 4.
Second Embodiment
[0052] FIG. 4 is a front view of pump element PE according to a
second embodiment.
[0053] In the first embodiment, the multiple through-holes 22a and
23a are formed in the outer and inner rotors 22 and 23 at equal
distance in the circumferential direction. It is, however, not
necessary to arrange the through-holes at equal distance. As shown
in FIG. 4, the through-holes 23a can be formed in the inner rotor
23 at non-equivalent distances in the circumferential direction.
Although only the through-holes for the inner rotor 23 are shown in
FIG. 4, the through-holes 22a can be formed in the outer rotor 22
at non-equivalent distances in the circumferential direction, as in
the same manner for the inner rotor 23.
Third Embodiment
[0054] FIG. 5 is a front view of a rotor 25 according to a third
embodiment.
[0055] The third embodiment is an embodiment in which the present
invention of the rotary pump is applied to a vane type pump.
[0056] The vane type pump has, as shown in FIG. 5, a rotor 25
formed with multiple vane grooves 25a at its outer periphery at
equal distance in the circumferential direction, and vanes 26
respectively and movably inserted into the vane grooves 25a.
[0057] When the multiple through-holes 25b are formed in the rotor
25 and the rotor 25 is floated, as in the same manner to the first
embodiment, metal contacts with other parts can be prevented and
thereby the problems of the abnormal wear and seizures and the like
can be suppressed.
[0058] In this embodiment as shown in FIG. 5, the through-holes 25b
are formed at both sides to the respective vanes 26 and the
circumferential distance of the through-holes 25b between the
respective vanes 26 is arranged to be equal to each other. However,
the circumferential distance of the through-holes 25b is not
necessary to be equal but to be non-equivalent.
Other Embodiments
[0059] The above embodiments are explained as those embodiments in
which the fuel supply apparatus of the invention is used in the
fuel injection pump of the common rail fuel injection system for
diesel engines. The present invention is not limited to these
embodiments, and the present invention can be used for a fuel pump
for a gasoline engine.
* * * * *