U.S. patent application number 12/669670 was filed with the patent office on 2010-08-19 for high-pressure pump for a fuel system of an internal combustion engine.
Invention is credited to Markus Becker, Martin Kirschner, Guenther Schnalzger, Bernd Schroeder.
Application Number | 20100206252 12/669670 |
Document ID | / |
Family ID | 39712674 |
Filed Date | 2010-08-19 |
United States Patent
Application |
20100206252 |
Kind Code |
A1 |
Schroeder; Bernd ; et
al. |
August 19, 2010 |
HIGH-PRESSURE PUMP FOR A FUEL SYSTEM OF AN INTERNAL COMBUSTION
ENGINE
Abstract
The invention relates to a high-pressure pump for a fuel system
of an internal combustion engine, having at least one inlet valve
device with a valve element, a valve seat for the valve element,
and an actuating tappet which can positively push the valve element
in an opening direction. In order to create a high-pressure pump
for a fuel system of an internal combustion engine which can be
produced even more cost-effectively and which has a lower level of
wear and therefore a longer service life, it is proposed that the
valve element have a positioning mechanism which centers the valve
element on the valve seat when the valve element comes into contact
or is in contact with the valve seat.
Inventors: |
Schroeder; Bernd;
(Esslingen, DE) ; Becker; Markus; (Immenstadt,
DE) ; Schnalzger; Guenther; (Blaichach, DE) ;
Kirschner; Martin; (Blaichach, DE) |
Correspondence
Address: |
RONALD E. GREIGG;GREIGG & GREIGG P.L.L.C.
1423 POWHATAN STREET, UNIT ONE
ALEXANDRIA
VA
22314
US
|
Family ID: |
39712674 |
Appl. No.: |
12/669670 |
Filed: |
May 27, 2008 |
PCT Filed: |
May 27, 2008 |
PCT NO: |
PCT/EP2008/056468 |
371 Date: |
January 19, 2010 |
Current U.S.
Class: |
123/90.5 |
Current CPC
Class: |
F02M 63/0017 20130101;
F02M 63/0022 20130101; F02M 63/0071 20130101; F02M 63/004 20130101;
F02M 63/007 20130101; F02M 59/367 20130101; F02M 63/0035 20130101;
F02M 2200/02 20130101 |
Class at
Publication: |
123/90.5 |
International
Class: |
F01L 1/14 20060101
F01L001/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 20, 2007 |
DE |
10 2007 034 038.0 |
Claims
1-10. (canceled)
11. A high-pressure pump for a fuel system of an internal
combustion engine, comprising: at least one inlet valve device with
a valve element; a valve seat for the valve element; an actuation
tappet, which can press the valve element by force in an opening
direction; and characterized in that the inlet valve device has
positioning means for the inlet valve device, which center the
valve element on the valve seat when the valve element comes into
contact with or when the valve element is in contact with the valve
seat.
12. The high-pressure pump as defined by claim 11, wherein the
positioning means include a spherical, preferably
spherical-segmental first contact region that is present on the
valve element.
13. The high-pressure pump as defined by claim 11, wherein the
positioning means include a conical first contact region that is
present on the valve element.
14. The high-pressure pump as defined by claim 11, wherein the
positioning means include a second contact region, which is present
on the valve seat and is embodied as complementary to the first
contact region and/or conically.
15. The high-pressure pump as defined by claim 12, wherein the
positioning means include a second contact region, which is present
on the valve seat and is embodied as complementary to the first
contact region and/or conically.
16. The high-pressure pump as defined by claim 13, wherein the
positioning means include a second contact region, which is present
on the valve seat and is embodied as complementary to the first
contact region and/or conically.
17. The high-pressure pump as defined by claim 11, wherein the
actuation tappet is supported in "overhung" fashion with radial
play in a housing of the inlet valve device or of the high-pressure
pump.
18. The high-pressure pump as defined by claim 14, wherein the
actuation tappet is supported in "overhung" fashion with radial
play in a housing of the inlet valve device or of the high-pressure
pump.
19. The high-pressure pump as defined by claim 11, wherein the
actuation tappet and the valve element are two separate parts,
which at least when the valve element is pressed by force in the
opening direction are fixed radially to one another by means of
radially acting fixation means.
20. The high-pressure pump as defined by claim 14, wherein the
actuation tappet and the valve element are two separate parts,
which at least when the valve element is pressed by force in the
opening direction are fixed radially to one another by means of
radially acting fixation means.
21. The high-pressure pump as defined by claim 19, wherein the
radial fixation means include a peg on the one part and a
complementary recess in the other part.
22. The high-pressure pump as defined by claim 21, wherein the peg
and the recess are conical.
23. The high-pressure pump as defined by claim 17, wherein on an
end of the actuation tappet remote from the valve element, the pump
has a damping spring.
24. The high-pressure pump as defined by claim 19, wherein on an
end of the actuation tappet remote from the valve element, the pump
has a damping spring.
25. The high-pressure pump as defined by claim 21, wherein on an
end of the actuation tappet remote from the valve element, the pump
has a damping spring.
26. The high-pressure pump as defined by claim 22, wherein on an
end of the actuation tappet remote from the valve element, the pump
has a damping spring.
27. The high-pressure pump as defined by claim 23, wherein on a
side of the valve element remote from the actuation tappet, a valve
spring is disposed, which urges the valve element in the closing
direction; and that the damping spring and the valve spring
cooperate in such a way that a motion of the actuation tappet in
the closing direction is damped, at least beyond a defined
remaining stroke.
28. The high-pressure pump as defined by claim 24, wherein on a
side of the valve element remote from the actuation tappet, a valve
spring is disposed, which urges the valve element in the closing
direction; and that the damping spring and the valve spring
cooperate in such a way that a motion of the actuation tappet in
the closing direction is damped, at least beyond a defined
remaining stroke.
29. The high-pressure pump as defined by claim 25, wherein on a
side of the valve element remote from the actuation tappet, a valve
spring is disposed, which urges the valve element in the closing
direction; and that the damping spring and the valve spring
cooperate in such a way that a motion of the actuation tappet in
the closing direction is damped, at least beyond a defined
remaining stroke.
30. The high-pressure pump as defined by claim 26, wherein on a
side of the valve element remote from the actuation tappet, a valve
spring is disposed, which urges the valve element in the closing
direction; and that the damping spring and the valve spring
cooperate in such a way that a motion of the actuation tappet in
the closing direction is damped, at least beyond a defined
remaining stroke.
Description
PRIOR ART
[0001] The invention relates to a high-pressure pump for a fuel
system of an internal combustion engine, having at least one inlet
valve device with a valve element, a valve seat for the valve
element, and an actuation tappet, which can press the valve element
by force in an opening direction.
[0002] It is known to embody high-pressure pumps with such inlet
valve devices, also known as quantity control valves. Such known
quantity control valves have means for precise radial guidance of
an actuation tappet and typically include a valve element with a
flat seat. Moreover, for varying a pumping rate of the
high-pressure pump, they can either be kept in an open position, or
put into such an open position by force, by means of current
supplied to an electromagnetic actuation device. Such quantity
control valves are therefore also called quantity control valves
that are closed when without current.
DISCLOSURE OF THE INVENTION
[0003] It is the object of the invention to create a high-pressure
pump for a fuel system of an internal combustion engine that can be
produced even more economically and that has low wear and thus a
longer service life.
[0004] This object is attained by a high-pressure pump having the
characteristics of claim 1. Advantageous refinements are recited in
dependent claims. Characteristics important to the invention are
also found in the ensuing description and the drawings, and the
characteristics may be important alone or in various combinations,
without explicit reference to this being made again.
[0005] In the realization of the high-pressure pump of the
invention, by means of the more-precise positioning of the valve
element relative to the valve seat, a more-uniform fluid flow over
the entire circumference of the valve element is attained. This
leads to reduced turbulence of a fuel flowing past the valve
element, resulting in a higher flow rate when the inlet valve
device is open.
[0006] It is especially preferred that the positioning means
include a spherical, preferably spherical-segmental first contact
region that is present on the valve element. A spherical shape of
the valve element makes it possible to lessen the flow deflection
when the inlet valve device is open, so that the flow rate can be
increased further. Moreover, with the aid of a spherical or
spherical-segmental contact region, the positioning means can be
realized especially simply. In particular, no additional components
have to be provided.
[0007] On the other hand, it can also be provided that the
positioning means include a conical first contact region that is
present on the valve element. In this way, a high-pressure pump
that can be produced simply, quickly and economically can be
furnished.
[0008] It is furthermore preferred that the positioning means
include a second contact region, present on the valve seat, that is
embodied as complementary to the first contact region and/or
conically. As a result, a reliable, replicable closure of the inlet
valve device with little wear and thus great durability is
attained. If the first contact region of the valve element is
embodied as spherical and the second contact region of the valve
seat is embodied conically, then complicated manufacturing steps,
such as grinding operations, are not necessarily required.
[0009] The actuation tappet can be supported in "overhung" fashion
with radial play in a housing of the inlet valve device or of the
high-pressure pump. Thus a precise radial guidance of the actuation
tappet is dispensed with, which makes production simpler. As a
result, because of the reduced friction, better axial mobility of
the actuation tappet and hence a fast-switching inlet valve device
are obtained. Moreover, the components required for the radial
guidance can be dispensed with, so that the number of parts and
thus the production costs of the high-pressure pump are
reduced.
[0010] It may be provided that the actuation tappet and the valve
clement are two separate parts, which at least when the valve
element is pressed by force in the opening direction are fixed
radially to one another by means of radially acting fixation means.
The embodiment by means of two separate parts facilitates the
manufacture of these parts and their assembly. Nevertheless, with
the inlet valve device open by force, decentering of the valve
element and the actuation tappet relative to one another is
avoided. A uniform flow around the valve element is accordingly
ensured not only when the inlet valve device is opened
automatically but also when it is opened by force.
[0011] The radial fixation means can include a peg on the one part
and a complementary recess in the other part. This realization of
the fixation means functions reliably and is low in wear.
Production is especially simple if the peg is provided on the
actuation tappet and the complementary recess is provided on the
valve element.
[0012] It is especially preferred that the peg and the recess are
conical. Such fixation means can in fact be produced especially
simply and yet still function reliably, since any decentering that
has occurred can be reliably eliminated.
[0013] If it is provided that on an end of the actuation tappet
remote from the valve element, the pump has a damping spring, then
a hard impact of the actuation tappet upon closure of the valve
device is avoided. This leads to a further reduction in wear and
operating noise.
[0014] It is especially preferred that on a side of the valve
element remote from the actuation tappet, a valve spring is
disposed, which urges the valve element in the closing direction;
and that the damping spring and the valve spring cooperate in such
a way that a motion of the actuation tappet in the closing
direction is damped, at least beyond a defined remaining stroke. By
this kind of adaptation of the damping spring and the valve spring,
reliable closure of the valve device, that is, the seating of the
valve element on the valve seat, is assured, and at the same time
the return motion of the actuation tappet upon closure of the inlet
valve device that was initially opened by force is damped.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Below, exemplary embodiments of the present invention are
described in further detail with reference to the accompanying
drawings. Identical elements have the same reference numerals and
as a rule are described in detail only once. In the drawings, in
schematic illustration:
[0016] FIG. 1 shows a fuel system of an internal combustion engine
with a high-pressure pump in accordance with a preferred embodiment
of the present invention;
[0017] FIG. 2 shows an inlet valve device of the high-pressure pump
of FIG. 1 in a closed state;
[0018] FIG. 3 shows a detail of FIG. 2 for an automatically opened
inlet valve device;
[0019] FIG. 4 is a view similar to FIG. 3, but with the inlet valve
device opened by force; and
[0020] FIG. 5 shows a further detail of FIG. 2 for an inlet valve
device opened by force.
EMBODIMENTS OF THE INVENTION
[0021] FIG. 1 shows a fuel system 1 of an internal combustion
engine in a highly schematic illustration. A high-pressure pump 3
communicates with a fuel tank 9 upstream via an intake line 4, a
prefeed pump 5, and a low-pressure line 7. Downstream, a
high-pressure reservoir 13 ("rail" 13) is connected to the
high-pressure pump 3 via a high-pressure line 11. The high-pressure
pump 3 has an inlet valve device 14 with an electromagnetic
actuation device 15. The inlet valve device 14 is disposed
hydraulically between the low-pressure line 7 and a pump cylinder
17. Inlet openings 16 of the inlet valve device 14 are connected to
the low-pressure line 7, and the pump cylinder 17 communicates with
outlet openings 18 of the inlet valve device 14. The pump cylinder
17 and the high-pressure line 11 communicate with one another via
an outlet valve 19 embodied as a check valve. The pump cylinder 17
and a piston 21 supported displaceably in it define a work chamber
23. The piston 19 is acted upon by an eccentric portion 25 of a
drive shaft (not identified by reference numeral).
[0022] In operation of the fuel system 1, the prefeed pump 5 pumps
fuel from the fuel tank 9 into the low-pressure line 7. The piston
21 moves back and forth, driven by the rotating eccentric portion
25 (arrow 27), which leads to a periodically repeating enlargement
and reduction in size of the work chamber 23. If the work chamber
23 is becoming larger, the piston 21 is in an intake stroke, and
fuel is then aspirated into the work chamber via the inlet valve
device 15. The inlet valve device 14 opens automatically because of
a pressure difference, caused by the intake stroke, between the
inlet openings 16 and the outlet openings 18, and thus connects the
low-pressure line to the pump cylinder 17. When the work chamber 23
is decreasing in size (piston 21 is in a pumping stroke), the fuel
located in the work chamber 23 is subjected to a pressure. This
pressure also acts on the inlet valve device 14 and the outlet
valve 19. If the actuation device 15 of the inlet valve device 14
is not receiving current, then the inlet valve device can close
automatically at the end of the intake phase, because of the force
of a valve spring 45 (see FIG. 2). If the opening pressure of the
outlet valve 17 is exceeded, that valve opens, so that the fuel is
pumped into the high-pressure line 11.
[0023] To limit a pumping rate of the high-pressure pump 3, current
can be supplied to the electromagnetic actuation device 15 during
the intake stroke, so that at the beginning of the pumping stroke
that follows the intake stroke as well, the inlet valve device 14
remains open by force. The fuel is then pumped back into the
low-pressure line 7. If the current supply to the electromagnetic
actuation device 15 is already stopped during the pumping stroke,
the inlet valve device 14 closes, and the fuel that still remains
in the work chamber 23 is pumped into the high-pressure line 11 via
the outlet valve 19. By a choice of the instant at which the
current supply to the electromagnetic actuation device 15 is ended,
the effective pumping volume of a pumping stroke is thus
defined.
[0024] FIG. 2 shows the construction of the inlet valve device 14.
The inlet valve device has a valve element 31, a valve seat 33, and
an actuation tappet 35. The actuation tappet 35 is guided radially
inside a housing 37 with considerable play, of up to several tenths
of a millimeter. When the inlet valve device 14 is open, the valve
element 31 likewise has a radial play. In that sense, the valve
element 31 and the actuation tappet 35, except in their closed
terminal positions, are supported in "overhung" fashion inside the
inlet valve device 14.
[0025] The inlet openings 16, which extend radially and into which
fuel can flow out of the low-pressure line 7, are located in the
housing 37, above the valve element 31 in terms of the illustration
in FIG. 2. The inlet openings 16 extend at a right angle to a
longitudinal axis 39. While in the operating state shown in FIG. 2,
the actuation tappet 35 rests on a top side 41 at the valve element
31, a valve spring 45 is disposed on an underside 43 of the valve
element 31; this spring is retained by a spring holder 47
structurally connected to the housing. The spring holder 47 has the
outlet openings 18.
[0026] On its top side 41, the valve element 31 has a first
spherical-segmental, convex contact region 49. A second contact
region 51 of the valve seat 33 has a complementary
spherical-segment-like and concave shape that is complementary to
the shape of the first contact region 49. The two contact regions
49, 51 together form positioning means 52, which center the valve
element 31 on the valve seat 33. In an embodiment not shown, the
second contact region 51 is conical and the first contact region 49
is again spherical-segmental, and in a further embodiment not
shown, both contact regions 49, 51 are conical. In principle,
instead of a spherical-segment-like shape, some other spherical
form of the first contact region 49 or of the second contact region
51 may be provided; the latter shape must be adapted to the first
in order to ensure reliable closure of the inlet valve device
14.
[0027] The actuation tappet 35 has a conical peg 53 on its end
oriented toward the valve element 31. There is also a recess 55 in
the top side 41 of the valve element 31, the shape of which recess
is complementary to the conical shape of the peg 53. The peg 53 and
the recess 55 form radial fixation means 57.
[0028] On its side remote from the valve element 31, the actuation
tappet 35 has an armature 59 solidly connected to it. The armature
is movable back and forth inside a capsule 61 along the
longitudinal axis 39. A coil 63 is disposed around the capsule 61,
offset somewhat downward toward the valve element 31 relative to
the armature 59, and is covered toward the outside by a housing
jacket 65 and a covering disk 67. Between the armature 59 and the
housing 37, there is a remanent air gap disk 69, throughout the
actuation tappet 35 protrudes. The armature 59, on its side remote
from the housing 37, has a recess 71, in which, depending on the
operating state of the inlet valve device 14, a damping spring 73
is located either in part or entirely. The inlet valve device 14
furthermore has a plug element 75, connected electrically to the
coil 63, for the electrical connection of the coil 63, for instance
to an engine control unit. The inlet valve device 14 thus has a
magnet group 77, which includes the plug element 75, the coil 63,
the housing jacket 65, and the covering disk 67.
[0029] The mode of operation of the inlet valve device 14 will be
described in further detail below in conjunction with FIGS. 2
through 5 for various operating states (closed, automatically, and
open by force).
[0030] The closed state shown in FIG. 2 of the inlet valve device
14 occurs when the inlet valve device 14 is not supplied with
current, or in other words no current is flowing through the coil
63, and a pressure difference between a pressure at the inlet
openings 16 and a pressure at the outlet openings 18 is slight or
zero. In that case, a force exerted by the valve spring 45 on the
valve element 31 counter to an opening direction 79 is greater than
the sum of the force exerted on the valve element 31 by the damping
spring 73 via the actuation tappet 35 and the force exerted on the
valve element 31 in the opening direction 79 by the pressure
difference. This yields a resultant force, acting counter to the
opening direction 79, which presses the valve element 31 against
the valve seat 33.
[0031] If the piston 21 is in the intake stroke, then the pressure
prevailing at the outlet openings 18 of the inlet valve device 14
decreases, and the pressure difference between the inlet openings
16 and the outlet openings 18 increases. If the sum of the force of
the damping spring 73 and the compressive force exerted on the
valve element 31 attains a value which exceeds the force of the
valve spring 45, then the valve element 31 moves away from the
valve seat 33, and the inlet valve device 14 opens. In the ideal
case, the opening motion of the valve element 31 extends parallel
to the longitudinal axis 39. However, because of transverse forces
that may be caused by the valve spring 45 or by an asymmetrical
flow around the valve element 31, the valve element 31 may also
open in slightly tilted fashion; that is, a deviation in the
opening motion, from the course that is parallel to the
longitudinal axis 39, is possible. After the opening of the inlet
valve device 14, the actuation tappet 35, which because of its
relatively high mass in comparison to the valve element 31 is
sluggish, moves somewhat toward the valve element 31, driven by the
valve spring 73, but without touching the valve element. The state
shown in FIG. 3 is now established.
[0032] If in operation of the high-pressure pump a pumping rate of
the high-pressure pump is to be reduced, then typically current is
supplied to the coil 63 already during the intake stroke. As a
result of this current supply, a magnetic flux is created in the
armature 59 and leads to the buildup of a magnetic force there that
acts essentially parallel to the longitudinal axis 39 toward the
valve element 31--that is, in the opening direction 79. Because of
the magnetic force, the armature 59 together with the actuation
tappet 35 moves toward the valve element 31. The farther the
actuation tappet 35 moves toward the valve element 31, the more
deeply does the peg 53 of the actuation tappet 35 protrude into the
recess 55 in the valve element 31. As a result, a radial freedom of
motion of the valve element 31 relative to the actuation tappet 35
is successively reduced, until finally, when the actuation tappet
35 is seated on the valve element 31, as shown in FIG. 4, it
becomes nearly zero. The fixation means 57, formed by the peg 53
and the recess 55, thus cause the actuation tappet 35 and the valve
element 31 to be radially fixed relative to one another, in the
operating state in which the inlet valve device 14 is open by
force.
[0033] As shown in FIG. 5, the damping spring 73, in the operating
state of the inlet valve device 14 in which it is open by force, is
prestressed with a slight force. In an embodiment not shown, in the
operating state of the inlet valve device 14 in which it is open by
force, the damping spring 73 is completely relaxed, and a gap is
created on one or both ends of the damping spring 73.
[0034] If the current flowing through the coil 63 is switched off
again, then the magnetic force acting on the armature 59
dissipates, and the valve spring 45 presses the valve element 31
toward the valve seat 33, parallel to the longitudinal axis 39.
During the motion of the valve element 31, a radial play of the
valve element 31 relative to the valve seat 33 decreases gradually,
because of the spherical shape of the two contact regions 49, 51.
Thus the valve element 31 is centered relative to the valve seat 35
during the closing motion.
[0035] At the end of the closing motion, the armature 59 presses
the damping spring 73 against the capsule 61, so that the damping
spring 73 is compressed, and the motion of the actuation tappet 35
is damped; the state of the inlet valve device 14 shown in FIG. 2
is then restored. The valve spring 45 and the damping spring 73 are
adapted to one another in such a way that on the one hand, the
motion of the actuation tappet 35 and of the armature 59, which
together have a comparatively high mass, is damped such that the
armature 59 does not strike the capsule 61 hard, and on the other,
the valve device 14 reliably closes.
* * * * *