U.S. patent application number 11/878975 was filed with the patent office on 2008-07-24 for transfer pump for injection of fuel at high pressure.
This patent application is currently assigned to SIEMENS AUTOMOTIVE HYDRAULICS SA. Invention is credited to Eric Martin, Florent Sellas.
Application Number | 20080175731 11/878975 |
Document ID | / |
Family ID | 37986503 |
Filed Date | 2008-07-24 |
United States Patent
Application |
20080175731 |
Kind Code |
A1 |
Sellas; Florent ; et
al. |
July 24, 2008 |
Transfer pump for injection of fuel at high pressure
Abstract
A transfer pump for the injection of fuel under high pressure of
the type comprising a piston (10) providing the hydraulic liquid to
a deformable bellows (14), the deformations of said bellows (14) in
a cylindrical chamber (20) filled with fuel giving rise to a high
pressure pumping effect of said fuel; a cam (5) provided with lugs
(6) carried by a drive shaft (1), is characterized in that the oil
portion of the pump comprises: the portion of the drive shaft (1)
bearing the cam (5); the cam (5) and its lugs (6); the roller (7)
with its shaft (8) and its roller bearing (9) carried by a bearing
member (12), by which roller the cam(5) bears on the piston (10);
as well as the upper portion of said piston (10); such that all the
mechanical drive portion and angle change are bathed in the oil of
the oil portion.
Inventors: |
Sellas; Florent; (Colombes,
FR) ; Martin; Eric; (Saint Denis, FR) |
Correspondence
Address: |
YOUNG & THOMPSON
209 Madison Street, Suite 500
ALEXANDRIA
VA
22314
US
|
Assignee: |
SIEMENS AUTOMOTIVE HYDRAULICS
SA
ASNIERES SUR SEINE
FR
|
Family ID: |
37986503 |
Appl. No.: |
11/878975 |
Filed: |
July 30, 2007 |
Current U.S.
Class: |
417/394 |
Current CPC
Class: |
F04B 43/084 20130101;
F04B 1/0413 20130101; F04B 1/0404 20130101; F02M 2200/31 20130101;
F02M 59/102 20130101 |
Class at
Publication: |
417/394 |
International
Class: |
F04B 43/10 20060101
F04B043/10 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 2006 |
FR |
06/07181 |
Claims
1. Transfer pump for injection of high pressure fuel of the type
comprising a piston (10) supplying hydraulic liquid to a deformable
bellows (14), the deformations of said bellows (14) in a
cylindrical chamber (20) filled with fuel, giving rise to a pumping
effect at high pressure of said fuel; a cam (5) provided with lugs
(6) carried by a drive shaft (1), characterized by the fact that
the oil portion of the pump comprises: the portion of the drive
shaft (1) bearing the cam (5); the cam (5) and its lugs (6); the
roller (7) with its shaft (8) and its roller bearing (9) carried by
a bearing member (12), by which roller the cam (5) bears on the
piston (10); as well as the upper portion of said piston (10): such
that all the mechanical drive portion and the angle change bathe in
the oil of the oil portion.
2. Transfer pump according to claim 1, in which the sealing between
the oil portion and the drive shaft (1) is ensured by a simple
joint with loops (30).
3. Transfer pump according to claim 1, in which the chamber (21) of
the housing (3) in which the cam (5) works is connected to a volume
compensator (26).
4. Transfer pump according to claim 3, in which a second volume
compensator (27) is connected to the bore (22) in which operate the
roller (7), the bearing member (12) and the upper portion of the
piston (10).
5. Pump according to claim 4, in which the piston (10) comprises an
internal bore (10a) communicating with said bore (22) by an opening
(24) and comprises a non-return valve (28); such that the volume of
oil placed under pressure is small.
6. Pump according to claim 5, in which the piston (10) sides in a
sleeve (13) provided at its base with a disc (17) having a bore
(19) in which slides a finger (18) carried by a member (15) fixed
to the base of the bellows (14); so as to ensure the guidance of
said bellows (14) during its successive deformations.
7. Pump according to claim 1, in which the shaft drive mechanism
for the shaft (1) is a freewheel mechanism.
Description
[0001] The present invention relates to improvements in pumps for
the injection of fuel at high pressure, of the type comprising a
piston delivering hydraulic fluid into a deformable element such as
a bellows, the deformations of said bellows in a cylindrical
chamber filled with fuel giving rise to a pumping effect of said
fuel toward high pressure injectors.
[0002] Pumps of this type have been described in U.S. Pat. No.
2,826,068, 2,828,240 and patent application 06/02594 in the name of
the applicant.
[0003] The present invention has for its object to provide a
solution to two problems which arise from mounting this type of
pump on motors.
[0004] The first problem arises because in certain motors it is
necessary to integrate the direct injection high pressure injection
pump at the end of the camshaft or on the transmission pulleys and
not directly on the cylinder head. In the case of the utilization
of a single piston pump an angle change is necessary, which gives
rise to various drawbacks such as: the size of the pump, the
requirement for an adaptation housing, lubricating means, noise,
wear of the elements etc.
[0005] The second problem arises because for such a mounting, it is
necessary to provide an operating play between the drive means of
the pump and the latter, of the Oldham joint type, for example.
When the pump is single piston, there are produced large vibrations
from the resistive couple of the pump, possibly even with negative
peaks, which vibrations can give rise to loosening the contact
surfaces which transmit the couple, which loosening generates
couple returns in the motor shaft. These couple returns constitute
a disturbing element for the operation of the motor such as:
coupling jolts on the camshaft or timing chain, unacceptable
noise.
[0006] The solution of the first problem consists in designing the
pump such that the oil portion comprises not only the pumping
portion but also all the drive portion and angle change.
[0007] This has the advantages: on the one hand suppression of
dynamic sealing in translation on the transfer single piston pump
which is very cumbersome and remains difficult to control; on the
other hand all the drive elements will be perfectly lubricated.
Moreover, the increase of the closed cycle oil volume increases the
resistance to oil temperature and decreases the risks of
heating.
[0008] The solution of the second problem consists in providing a
free wheel between the drive shaft and the cam.
[0009] By way of non-limiting example, and to facilitate
understanding of the invention, there are shown the following
drawings, in which:
[0010] FIG. 1 is a cross-sectional view of an embodiment of the
transfer pump according to the invention,
[0011] FIG. 2 is a cross-sectional view on A-A of FIG. 1,
[0012] FIG. 3 is a fragmentary view showing a modification of FIG.
2.
[0013] Referring to these drawings, it will be seen that the pump
according to the invention comprises a drive shaft 1, connected by
an Oldham joint 2 to the drive member (camshaft for example) not
shown.
[0014] The shaft is carried by a housing 3.
[0015] The shaft carries a cam 5, which, in the illustrated
example, comprises four lugs 6.
[0016] A piston 10 comes to bear by means of a spring 11 against
the cam 5, with interposition between the piston 10 and the cam 5
of roller 7, carried by a shaft 8 by means a needle bearing 9.
[0017] Preferably, a bearing member 12 is interposed between the
roller 7 and the piston 10. This bearing member 12 is preferably
constituted by two oppositely facing cups 12a, 12b, separated by a
partition 12c provided with a plurality of openings 23.
[0018] The external wall of the bearing member 12 comprises
recesses which facilitate the passage of oil about this member
12.
[0019] The piston 10, urged by spring 11, slides in a sleeve
13.
[0020] The end 13a of the sleeve 13 enters a bellows 14, provided
at its lower end with a circular member 15, urged by a return
spring 16.
[0021] The interior within the sleeve 13 and at its end is disposed
a disc 17 which comprises at its center a bore 19, in which slides
a finger 18, carried by said circular member 15, at its center.
This ensures correct guiding of the bellows 14 during its
successive elongations. The guidance of the bellows 14 permits
decreasing and best adjusting the diameter of the chamber 20 in
which said bellows expands; this chamber 20 being filled with
fuel.
[0022] In FIG. 1 it is seen that the cam 5 turns within a circular
chamber 21 provided within the housing 3.
[0023] This chamber 21; the bore 22 within which slides the roller
7, the bearing member 12 and the upper portion of the piston 10;
the internal bore 10a of said piston; the internal bore of the
sleeve 13 and the interior of the bellows 14 are filled with a
hydraulic liquid. This liquid passes about the member 12 and also
within it where it traverses the partition 12a through the openings
23; then it enters the internal bore 10a of the piston 10 through
the opening 24 and passes through the disc 17 by its openings
25.
[0024] This ensures good communication between them, of the various
elements filled with oil.
[0025] There is this obtained a relatively great volume of the
volume of oil which his continually pumped, which improves the
lifetime of this oil and decreases the risk of heating.
[0026] To avoid the effects of pulsations adapted to be provoked by
the movements of the lugs 6 of the cam 5, there can preferably be
used a volume compensator 26, which communicates with the chamber
21 in which the cam 5 acts (FIG. 1).
[0027] For the same reason, there can be provided a volume
compensator 27, which communicates with the bore 22 (FIG. 2).
[0028] Moreover, the non-return valve 28 is disposed in the
internal bore 10a of the piston 10.
[0029] This has the result that only the portion 29 of said bore
10a, located downstream of the non-return valve 28, is placed under
pressure and hence only a small volume of oil is placed under
pressure, whilst the rest of the volume of oil is not pressurized.
During rising movement of the piston 10, under the action of the
return spring 11, the communication is re-established between the
oil which has been pressurized and all the rest which has not
been.
[0030] To contributes to avoiding heating of the oil.
[0031] As the shaft 1 is driven by a freewheel mechanism, the
shocks which are transmitted to the came 5 are not transmitted to
the drive shaft 1.
[0032] The sealing of the oil portion of the pump is ensured by a
simple joint with loops 30 disposed between the shaft 1 and housing
3.
[0033] All the components of the mechanical drive portion: cam 5,
roller 7 and its roller bearing 9, bearing member 12 sliding in the
bore 22, are immersed in the oil and are perfectly lubricated.
[0034] FIG. 3 shows a modified embodiment of the upper portion of
FIG. 2, showing the drive mechanism above the cam 5.
[0035] In this figure, the same elements bear the same reference
numerals.
[0036] The cam 5 is, in this example, of one piece with the motor
shaft 1, the transmission by Oldham joint 2 comprising a freewheel
mechanism 3.
[0037] The portion forming a cam 5 comprises a cylindrical cup 32
in which will engage a cylindrical axle 31 with interposition
between said axle 31 and the internal wall of the cup, of a guide
element.
[0038] The roller bearing 4 carrying shaft 1 is located outside the
housing 3, the sealing joint with loops 30 being in the housing 3,
between the roller bearing 4 and the cam 5.
[0039] In this embodiment, the roller bearing 4 is not lubricated
by the hydraulic oil but by the motor oil.
* * * * *