U.S. patent application number 13/579190 was filed with the patent office on 2013-01-24 for high-pressure pump.
This patent application is currently assigned to ROBERT BOSCH GMBH. The applicant listed for this patent is Peter Boehland, Walter Fuchs, Uwe Iben, Andreas Illmann, Nestor Rodriguez-Amaya. Invention is credited to Peter Boehland, Walter Fuchs, Uwe Iben, Andreas Illmann, Nestor Rodriguez-Amaya.
Application Number | 20130022484 13/579190 |
Document ID | / |
Family ID | 43924861 |
Filed Date | 2013-01-24 |
United States Patent
Application |
20130022484 |
Kind Code |
A1 |
Fuchs; Walter ; et
al. |
January 24, 2013 |
HIGH-PRESSURE PUMP
Abstract
A high-pressure pump (1), which serves in particular as a radial
or inline piston pump for fuel injection systems of
air-compressing, auto-ignition internal combustion engines,
comprises a cylinder head (2) and a pump assembly (6). Here, the
cylinder head (2) has a cylinder bore (4) in which a pump piston
(5) of the pump assembly (6) is guided. Here, the pump piston (5)
delimits, in the cylinder bore (4), a pump working chamber (12).
Also provided is an inlet valve (20) which is integrated into the
cylinder head (2) and via which fuel can be conducted into the pump
working chamber (12). Metering of the fuel conducted into the pump
working chamber (12) can be achieved by actuation of the inlet
valve (20). Here, full charging of the pump working chamber (12)
may take place. It is however also possible for partial charging of
the pump working chamber (12) to be achieved by means of suitable
actuation of the inlet valve (20).
Inventors: |
Fuchs; Walter; (Stuttgart,
DE) ; Rodriguez-Amaya; Nestor; (Stuttgart, DE)
; Boehland; Peter; (Marbach, DE) ; Iben; Uwe;
(Gerlingen, DE) ; Illmann; Andreas; (Weil Der
Stadt, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fuchs; Walter
Rodriguez-Amaya; Nestor
Boehland; Peter
Iben; Uwe
Illmann; Andreas |
Stuttgart
Stuttgart
Marbach
Gerlingen
Weil Der Stadt |
|
DE
DE
DE
DE
DE |
|
|
Assignee: |
ROBERT BOSCH GMBH
Stuttgart
DE
|
Family ID: |
43924861 |
Appl. No.: |
13/579190 |
Filed: |
March 2, 2011 |
PCT Filed: |
March 2, 2011 |
PCT NO: |
PCT/EP11/53101 |
371 Date: |
August 15, 2012 |
Current U.S.
Class: |
417/490 ;
417/437 |
Current CPC
Class: |
F02M 59/48 20130101;
F04B 49/225 20130101; F04B 53/10 20130101; F02M 55/04 20130101;
F02M 59/102 20130101; F02M 59/367 20130101; F02M 59/366 20130101;
F02M 2200/315 20130101; F02D 41/3845 20130101; F04B 53/007
20130101; F02M 63/0035 20130101; F04B 53/22 20130101; F02M 59/466
20130101 |
Class at
Publication: |
417/490 ;
417/437 |
International
Class: |
F04B 7/04 20060101
F04B007/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 14, 2010 |
DE |
102010027745.2 |
Claims
1. A high-pressure pump (1) for fuel injection systems of
air-compressing, auto-ignition internal combustion engines, with at
least one cylinder head (2) and a pump assembly (6), wherein the
cylinder head (2) has a cylinder bore (4) in which is guided a pump
piston (5) of the pump assembly (6), wherein the pump piston (5) in
the cylinder bore (4) delimits a pump working chamber (12), wherein
an inlet valve (20) integrated in the cylinder head (2) is provided
via which fuel can be transferred to the pump working chamber (12)
and whereby, by control of the inlet valve (20), a metered feed of
the fuel guided into the pump working chamber (12) is possible.
2. The high-pressure pump as claimed in claim 1, characterized in
that the inlet valve (20) is formed as a magnetically controllable
inlet valve (20).
3. The high-pressure pump as claimed in claim 2, characterized in
that the inlet valve (20) is fixed to the cylinder head (2) by
means of a screw plug (21) screwed into the cylinder head (2) and
that the screw plug (21) is made of a ferromagnetic material.
4. The high-pressure pump as claimed in claim 1, characterized in
that a magnet coil (32) is provided, that current flowing through
the magnet coil (32) allows control of the inlet valve (20), and
that the magnet coil (32) can be cooled by fuel which can be
transferred via the inlet valve (20) to the pump working chamber
(12).
5. The high-pressure pump as claimed in claim 1, characterized in
that the inlet valve (20) comprises a valve body (23) and a valve
tappet (25) co-operating with the valve body (23) to form a seal
seat, wherein the valve tappet (25) lies against the cylinder head
(2), wherein a magnetically activatable solenoid plunger (30) is
provided and wherein the solenoid plunger (30) carries the valve
tappet (25) with it on magnetic actuation to open the seal seat
formed between the valve body (23) and the valve tappet (25).
6. The high-pressure pump as claimed in claim 5, characterized in
that an adjustment shim (29) is provided which serves to specify a
working air gap for the solenoid plunger (30).
7. The high-pressure pump as claimed in claim 1, characterized in
that a controller (38) is provided which controls the inlet valve
(20) as a function of movement of the pump piston (5) of the pump
assembly (6).
8. The high-pressure pump as claimed in claim 7, characterized in
that to reduce a filling of the pump working chamber (12) of the
pump assembly (6), the controller (38) at least one of: a) shortens
the control time at its end so that the inlet valve (20) is closed
before the pump piston (5) reaches a bottom dead center, or extends
the control time at its end so that the inlet valve (20) is closed
after the pump piston (5) reaches a bottom dead center, and b)
shortens the control time at its start so that the inlet valve (20)
is opened after the pump piston (5) reaches a top dead center.
9. The high-pressure pump as claimed in claim 1, characterized in
that the inlet valve (20) has a low pressure chamber (16) which is
formed in a recess (17) of the cylinder head (2) in which the inlet
valve (20) is arranged and in that at least one of the low pressure
chamber (16) is closed by a screw plug (21) of the inlet valve
(20), and that a supply channel (13) leading to the low pressure
chamber (16) is provided and that in the supply channel (13) is
arranged at least one of at least one choke (14, 15) and at least
one damping volume.
10. The high-pressure pump as claimed in claim 1, characterized in
that the inlet valve (20) has a closing spring (27) and that the
closing spring (27) has a high spring pretension.
11. The high-pressure pump as claimed in claim 1, characterized in
that the high-pressure pump is one of a radial and an in-line
piston pump.
Description
BACKGROUND OF THE INVENTION
[0001] The invention concerns a high-pressure pump, in particular a
radial or in-line piston pump. The invention concerns in particular
the field of fuel pumps for fuel injection systems of
air-compressing, auto-ignition internal combustion engines. The
high-pressure pump can however also be used as a piston pump to
deliver other suitable fluids.
[0002] DE 195 15 191 A1 discloses a high-pressure fuel pump. The
high-pressure fuel pump has a cylinder, the upper part of which
lies open towards the outside of the head cover which is part of
the engine housing. The remaining segment of the high-pressure fuel
pump is accommodated in a housing hole in the head cover. A pump
cam is mounted on a valve camshaft to drive an intake/exhaust valve
and drives the high-pressure fuel pump. As the time behavior with
which the pressurized fuel is expelled is controlled by activation
of a solenoid valve, the accuracy with which the fuel delivery is
controlled is also improved.
[0003] The high-pressure fuel pump disclosed in DE 195 15 191 A1 is
a pump choked on the suction side which has several disadvantages.
The disadvantages are high noise, poor controllability and the
occurrence of mechanical vibrations due to cavitations occurring in
the supply lines to the inlet valves. Pressure waves between a feed
metering unit and the suction valve have an unfavorable effect on
the function.
SUMMARY OF THE INVENTION
[0004] The high-pressure pump according to the invention has the
advantage that an improved design is achieved in which in
particular a metered fuel feed and compact design are possible. In
particular no feed metering unit or similar is required, leading to
a substantial cost reduction in production.
[0005] In contrast to high-pressure pumps with suction-side volume
flow control by means of a feed metering unit in combination with
spring-loaded intake valves, which have the drawback that at a high
pump speed, constant delivery cannot be guaranteed and that
pressure fluctuations in the low pressure circuit can lead to
noise, advantageously a cost reduction can be achieved by the
omission of a feed metering unit, even at high pump speeds a
constant delivery can be made possible and noise reduction can be
achieved by the avoidance of pressure fluctuations and possible
cavitation in the low pressure circuit.
[0006] In a conventional design, in particular in multi-piston
pumps with three or more pistons, the suction phases overlap.
Pressure fluctuations then lead to particularly great differences
in the quantity delivered. This can advantageously be avoided. Here
it is possible to exclude such differences in the pre-stored
quantity.
[0007] In particular a great cost advantage is achieved with a
high-pressure pump designed as a single piston pump. Even when
designed as a two-piston pump with a further actuator, the absence
of bores in the housing of the high-pressure pump partially
compensates for extra costs. One essential advantage of direct
control is the expansion of the pump rotation speed range and hence
an improvement in the efficiency of the high-pressure pump.
[0008] Also integration of the inlet valve into the cylinder head
allows a very small construction size. This also applies for very
high pressures, for example of 300 MPa (3000 bar) as conceivable
for application on trucks.
[0009] Advantageously the inlet valve is formed as a magnetically
controllable inlet valve. Furthermore it is advantageous that the
inlet valve is fixed to the cylinder head by means of a screw plug
screwed into the cylinder head, and that the screw plug is formed
of a ferromagnetic material. As a result the screw plug can serve
as a magnetic conductor which improves the efficiency of the
magnetic circuit and allows a high magnetic force.
[0010] Also it is advantageous for a magnet coil to be provided,
that the inlet valve can be controlled via current flowing through
the magnet coil, and that the magnet coil can be cooled by fuel
that can be transferred via the inlet valve to the pump working
chamber. Thus cooling of the magnet coil and further elements of
the magnetic circuit can be achieved by flushing with the fuel.
[0011] It is also advantageous that the inlet valve has a valve
body and a valve tappet co-operating with the valve body to form a
seal seat, wherein the valve tappet lies on the cylinder head,
wherein a magnetically activatable solenoid plunger is provided and
wherein the solenoid plunger carries the valve tappet with it on
mechanical activation to open the seal seat formed between the
valve body and the valve tappet. Thereby the magnetic force to
activate the inlet valve can be generated via the solenoid plunger,
wherein the screw plug advantageously serves as a magnetic
conductor. The inlet valve is here preferably closed when the
magnet coil is switched without current. If current flows through
the magnet coil of the magnet and the pump piston is for example at
the top dead center, then the inlet valve opens. On full filling,
the inlet valve is preferably open until the bottom dead center of
the pump piston. It is furthermore advantageous here that an
adjustment shim is provided which serves to specify a working air
gap and a residual air gap for the solenoid plunger. This allows a
modular design wherein by fitting of a suitable adjustment shim,
adaptation is possible to the respective application of the
high-pressure pump. This expands the application range of the
high-pressure pump, wherein simple adaptation and largely identical
design of the high-pressure pump are possible.
[0012] It is also advantageous that a controller is provided which
controls the inlet valve as a function of movement of the pump
piston of the pump assembly. Firstly it is advantageous that the
controller, to reduce the filling of the pump working chamber of
the pump assembly, shortens the control time at its end so that the
inlet valve is closed before the pump piston reaches the bottom
dead center, or extends the control time at its end so that the
inlet valve is closed after the pump piston reaches a bottom dead
center. Thus the control time can be reduced so that the inlet
valve is closed again before the pump piston reaches the bottom
dead center, which reduces the quantity of fuel flowing into the
pump working chamber. This can alternatively also be achieved in
that the injector valve is only closed after the reaching of the
bottom dead center, whereby the fuel transferred to the pump
working chamber is returned partly via the inlet valve in the
opposite direction by the movement of the pump piston. In the first
case the pressure fluctuations on the low pressure side are
reduced. In the second case preferably no cavities occur in the
working cylinder. The advantageous variant may be selected
specially depending on the application. A further possibility is
that the control time is shortened at its start so that the inlet
valve is opened only after the pump piston reaches a top dead
center. Thus the inlet valve is not opened immediately after the
top dead center, so that the quantity of fuel flowing into the pump
working chamber is also reduced. Here also a suitable combination
of control methods can be performed by the controller. For example
the control time can be shortened both at its start and at its end.
Thus advantageously partial fillings of the pump working chamber
can be achieved. Furthermore pressure fluctuations can be
influenced positively with regard to amplitude and frequency by one
or more chokes connected before the inlet valve. Also the quantity
regulation can be positively influenced. In this way the noise
behavior, which can be unfavorably affected by pressure
fluctuations in the low pressure, can be improved.
[0013] The inlet valve is preferably fitted with a closing spring
with a high spring pretension to achieve a high closing
dynamic.
BRIEF DESCRIPTION OF THE DRAWING
[0014] Preferred embodiment examples of the invention are described
in more detail in the description below with reference to the
enclosed drawing. This shows:
[0015] FIG. 1 a high-pressure pump in an extract, schematic, axial
cross section view corresponding to one embodiment example of the
invention.
DETAILED DESCRIPTION
[0016] FIG. 1 shows a high-pressure pump 1 in an extract,
schematic, axial cross section view corresponding to one embodiment
example of the invention. The high-pressure pump 1 can in
particular be designed as a radial or in-line piston pump. The
high-pressure pump 1 is particularly suitable as a fuel pump for
fuel injection systems of air-compressing, auto-ignition internal
combustion engines. A preferred use of the high-pressure pump 1
lies in a fuel injection system with a fuel distribution rail which
stores diesel fuel under high pressure. The high-pressure pump 1
according to the invention is however also suitable for other
applications. In particular the high-pressure pump can be used as a
piston pump to deliver suitable fluids, in particular fluids other
than fuel.
[0017] The high-pressure pump 1 has a pump housing which is mounted
on a cylinder head 2. The cylinder head 2 has a shoulder 3 which
protrudes into a bore in the pump housing. Here in the shoulder 3
is formed a cylinder bore 4 in which a pump piston 5 of a pump
assembly 6 is guided along an axis 7.
[0018] The high-pressure pump 1 also has a drive shaft 8 on which
is provided a cam 9. The cam 9 can here also be designed as a
multiple cam or as an eccentric segment of the drive shaft 8. In
operation the drive shaft 8 with the cam 9 rotates about a rotary
axis 10. Between the pump piston 5 of the pump assembly 6 and the
cam 9 is an active connection 11 which is illustrated by the double
arrow 11. For example via a roller shoe and a roller mounted in the
roller shoe, an actuation force can be transferred by the cam 9 to
the pump piston 5. A return of the pump piston 5 can take place via
a suitable tappet spring.
[0019] Thus the pump assembly 6 can be driven by the cam 9 of the
drive shaft 8. Depending on the design of the high-pressure pump 1,
further pump assemblies can also be driven by the cam 9. Also on
the drive shaft 8 can be provided further cams which serve to drive
further pump assemblies. Depending on the design, a high-pressure
pump 1 can thus be constructed as a radial or in-line piston
pump.
[0020] The pump piston 5 in the cylinder bore 4 delimits a pump
working chamber 12. A supply channel 13 serves to supply fuel which
is delivered therein by a pre-delivery pump. In the supply channel
13 are provided a first choke 14 and a second choke 15. The supply
channel 13 leads into a low pressure chamber 16 which is formed by
a recess 17 in the cylinder head 2.
[0021] The high-pressure pump 1 has an inlet valve 20. The low
pressure chamber 16 is here part of the inlet valve 20. The inlet
valve 20 is integrated in the cylinder head 2. The inlet valve 20
is arranged in the recess 17 of the cylinder head 2. The recess 17
is here closed by a screw plug 21. Thus the low pressure chamber 16
is closed to the environment. The screw plug 21 acts via a valve
part 22 on a valve body 23. The screw plug 21 is screwed into the
cylinder head 2 and through this presses the valve body 23 against
a contact surface 24 formed on the cylinder head 2. The screw plug
21, valve part 22 and valve body 23 of the inlet valve 20 are thus
fixed in a stationary manner. Also the screw plug 21 and valve part
22 are preferably formed of ferromagnetic material.
[0022] In the valve body 23 is guided a valve tappet 25. Here the
valve tappet 25 co-operates with a valve seat surface 26 formed on
the valve body 23 to form a seal seat. A valve spring 27 presses
the valve tappet 25 against the valve seat surface 26. The valve
spring 27 here acts via a valve element 28 and an adjustment shim
29 on a rotor 30. The rotor 30 is formed as a solenoid plunger 30.
The solenoid plunger 30 is connected with the valve tappet 25. Thus
the valve tappet 25 is pressurized by the pretension of the valve
spring 27. The valve tappet 25, valve element 28, adjustment shim
29 and solenoid plunger 30 of the inlet valve 20 are mobile
elements which are moved to open the inlet valve 20 on control of
the inlet valve 20.
[0023] The inlet valve 20 also has a magnet 31 with a magnet coil
32. The magnet coil 32 is electrically connected via electrically
conductive contact pins 33, 34 with pins 35, 36 of a plug 37. The
plug 37 here allows connection with a control unit 38. The control
unit 38 in this embodiment example serves as a controller 38. The
controller 38 can also be integrated in a central control unit. The
control unit 38 is connected with a rotary angle sensor 39 which
detects the momentary rotation angle of the drive shaft 8 and emits
this to the control unit 38. Via the rotary angle detected, there
is a direct connection to the momentary position of the pump piston
5. It can in particular be detected thus whether the pump piston 5
is at a top dead center at which the pump piston undergoes a
maximum stroke and the pump working chamber 12 has minimum volume.
Accordingly it can be detected whether the pump piston 5 is at a
bottom dead center at which the pump piston 5 has minimum stroke
and the volume of the pump working chamber 12 is maximum.
[0024] Current flowing through the magnet coil 32 generates a
magnetic flux. This magnetic flux is emitted by the magnet 31
wherein an amplification is possible via the ferromagnetic screw
plug 21. The magnetic flux also runs via the valve part 22, the
solenoid plunger 30 and where applicable further ferromagnetic
elements back to the screw plug 21. Between the solenoid plunger 30
and the valve part 22 there is a gap 40. The gap 40 firstly allows
displaceability of the solenoid plunger 30 and thus an adjustment
of the valve tappet 25 to activate the inlet valve 20. Secondly at
least one rest air gap remains as gap 40 in order to avoid, in
activated state, a so-called magnetic adhesion effect of the
solenoid plunger 30 on the valve part 22. In particular when the
power to the magnet coil 32 is switched off, the force of the valve
spring 27 can initiate a closure of the inlet valve 20 largely
without distortion. The maximum size of the gap 40 is specified by
the sum of the desired working air gap and the residual air gap.
Adjustment of the residual air gap and working air gap is possible
by suitable selection of valve element 28 and adjustment shim 29.
In particular the thickness of the adjustment shim 29 can
pre-specify the desired working air gap. The thickness of the
adjustment shim 29 thus specifies the stroke of the valve tappet
25. With unchanged geometry in the region of the valve seat surface
26, thus the opening cross section at the valve seat surface 26 can
be changed and hence also the possible throughflow into the pump
working chamber 12 set when the seal seat is opened. Thus the inlet
valve 20 can be adapted in relation to the application
concerned.
[0025] By actuating inlet valve 20, fuel can thus be guided from
the low-pressure chamber 16 to the pump working chamber 12.
Activation of the inlet valve 20 here takes place during a suction
stroke of the pump piston 5. During the delivery stroke of the pump
piston 5, the inlet valve 20 is preferably closed. Thus fuel under
high pressure is delivered via outlet valve 41--which can be
designed as a directional or non-return valve 41--into a
high-pressure line 42. The high-pressure line 42 is for example
connected with a fuel distribution rail.
[0026] If the inlet valve 20 is opened at approximately the top
dead center of a pump piston 5 and closed at the bottom dead center
of pump piston 5, a full filling of the pump working chamber 12 can
be achieved. However the inlet valve 20 can be controlled by the
controller 38 irrespective of the stroke or momentary position of
pump piston 5 during the suction phase. This allows also a partial
filling of the pump working chamber 12. There are several
possibilities for this which can be combined where applicable.
[0027] One possibility is to reduce the control time of the inlet
valve 20 so that the inlet valve 20 is closed again before the pump
piston 5 reaches the bottom dead center. Alternatively the control
time can also be extended beyond the reaching of the bottom dead
center. The inlet valve 20 is thus only closed after pump piston 5
reaches the bottom dead center so that part of the fuel is
delivered back from the pump working chamber 12 during the stroke
of the pump piston 5 in the direction back through the inlet valve
20. The other part of the fuel is delivered then via the
high-pressure line 42. The quantity of fuel delivered via the
high-pressure line 42 per pump stroke is thus reduced.
[0028] It should be noted that there is no shut-off control of fuel
to a tank or similar. Also in this way where applicable noise
behavior can be improved by damping pressure pulses. Adjustment is
possible via chokes 14, 15.
[0029] A further possibility of achieving a partial filling is that
the inlet valve is not opened immediately after pump piston 5
reaches the top dead center. This achieves a certain idle stroke of
the pump piston 5 so that the entirety of fuel flowing into the
pump working chamber 12 via the opening cross section of the opened
seat seal is thus reduced.
[0030] Thus advantageously through one or more chokes 14, 15 or
damping volumes connected before the intake valve, the pressure
fluctuations can be reduced with regard to amplitude and frequency
and the quantity control can be reduced. The chokes here allow a
large partial reflection and slight damping of pressure and
attenuation waves. Damping volumes allow a lower partial reflection
and greater damping of the pressure and attenuation waves. This is
dependent on the geometric design of the respective damping volume.
By opening and closing the inlet valve 20 or where applicable
several inlet valves designed corresponding to the inlet valve 20,
pressure and attenuation waves occur which run from the intake
valves to a delivery pump, in particular an electric fuel pump, and
are reflected there. The reflected waves can inter alia make
contact again on an opening process of the inlet valve 20 and thus
further influence the filled mass in the pump working chamber,
which can lead to delivery fluctuations of the high-pressure pump.
By use of damping volumes and chokes 14, 15 in the supply channel
13 and by matching these, such pressure waves can be reduced so far
that a constant delivery of the high-pressure pump 1 is guaranteed
within a certain tolerance range. The design and dimensioning here
depend on the area of application of the high-pressure pump 1 and
the connection to the pre-delivery pump.
[0031] Advantageously thus an intake valve 20 can be produced which
is closed in the unpowered state. This inlet valve 20 is integrated
in the cylinder head 2. The solenoid plunger principle can be
utilized here so that rapid opening and closing of the intake valve
20 can be achieved. Furthermore the suction choking can be shifted
into the working cylinder with deliberate utilization of an air
exhalation. The necessary dynamic can be guaranteed by one or more
connecting bores. A sufficiently high closing dynamic can be
achieved via a correspondingly high spring pretension of valve
spring 27. The cooling of the magnet 31 with the magnet coil 32 can
be achieved by flushing with fuel.
[0032] The invention is not restricted to the embodiment examples
described.
* * * * *