U.S. patent number 3,633,823 [Application Number 04/869,264] was granted by the patent office on 1972-01-11 for injection system for diesel engines.
This patent grant is currently assigned to Sulzer Brothers Ltd.. Invention is credited to Anton Steiger.
United States Patent |
3,633,823 |
Steiger |
January 11, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
INJECTION SYSTEM FOR DIESEL ENGINES
Abstract
The needle valve is seated against the valve seat by the
differential pressure of the fuel. Lifting of the needle valve is
caused by transmitting a control pressure sufficient to overcome
the differential pressure under the piston. This control pressure
is delivered via the control member which selectively opens and
closes the control line to the flow of pressure medium.
Inventors: |
Steiger; Anton (Illnau/ZH,
CH) |
Assignee: |
Sulzer Brothers Ltd.
(Winterthur, CH)
|
Family
ID: |
4416700 |
Appl.
No.: |
04/869,264 |
Filed: |
October 24, 1969 |
Foreign Application Priority Data
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|
|
|
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Nov 1, 1968 [CH] |
|
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16363/68 |
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Current U.S.
Class: |
239/94; 239/96;
239/95; 239/533.8 |
Current CPC
Class: |
F02M
47/02 (20130101); F02M 47/025 (20130101); F02M
47/046 (20130101); F02B 3/06 (20130101) |
Current International
Class: |
F02M
47/02 (20060101); F02M 47/00 (20060101); F02M
47/04 (20060101); F02B 3/06 (20060101); F02B
3/00 (20060101); F02m 045/10 () |
Field of
Search: |
;239/93,94,95,96,533 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: King; Lloyd L.
Assistant Examiner: Thieme; Reinhold W.
Claims
What is claimed is:
1. An injection system for a diesel engine comprising:
an injection valve for injecting fuel and having a valve seat at
one end and a bore spaced from said valve seat;
a valve needle in said valve for seating on said valve seat, said
valve needle having a piston thereon slidably mounted in said bore
in sealtight relation to divide said bore into a pair of
chambers;
a duct having pressurized fuel therein for pressing said valve
needle against said valve seat under the pressure of the fuel;
first means connecting the chamber of said pair of chambers remote
from said valve seat to a low pressure space; and
a single fuel duct in said valve communicating with both a space
upstream of said valve seat and a space upstream of said piston for
imposing a differential pressure on said needle to seat said needle
against said valve seat; and
means connected to said valve communicating with said bore on the
side of said piston closest to said valve seat for selectively
increasing the pressure therein to an amount greater than said
differential pressure to unseat said needle from said valve
seat.
2. An injection system as set forth in claim 1 further comprising
fuel storage means connected to said injection valve.
3. An injection system as set forth in claim 1 wherein said first
means maintains said remote chamber at atmospheric pressure.
4. An injection system as set forth in claim 1 wherein said control
member includes a rotary valve having a cylindrical control surface
and a duct therein for conveying the control pressure medium
therethrough to said control surface and a bush slidably and
rotatably mounting said control surface of said valve therein, said
bush having a duct therein for selective communication with said
rotary valve duct.
5. An injection system as set forth in claim 1 wherein said
injection valve includes a first housing part having said bore
therein to receive said valve needle and said piston and a second
housing part having a bore therein, and wherein said first means
includes a cylindrical part slidably mounted in said bore of said
second housing part against said piston and a fuel duct connected
at one end to a space upstream of said valve seat in said first
housing part and to a space in said bore of said second housing
part upstream of said cylindrical part.
6. An injection system comprising:
an injection valve for injecting fuel, said valve having a valve
seat at one end, a bore therein, and jet bores to one side of said
valve seat;
a valve needle in said valve for seating on said valve seat, said
valve needle having a piston at one end thereof mounted in said
bore in sealtight relation;
second means connecting the chamber of said pair of chambers
closest to said valve seat to a source of pressurized control
pressure medium of a pressure sufficient to move said piston and
said needle valve away from said valve seat, said means including a
control member for selectively connecting said closest chamber to
the source of pressurized control pressure medium.
7. An injection system as set forth in claim 6 wherein said means
includes a rotary valve having a control surface and a duct therein
for conveying a control pressure medium therethrough to said
control surface, and a bush mounted about said control surface and
having a duct therein for conveying the control pressure medium to
said bore of said injection valve.
8. An injection system as set forth in claim 7 wherein said control
surface includes a triangular recess communicating with said duct
in said rotary valve and a peripherally extending recess
communicating to the exterior of said rotary valve.
9. An injection system as set forth in claim 7 wherein said bush is
adjustably relative to said rotary valve in a circumferential
direction and a longitudinal direction.
10. An injection system as set forth in claim 6 wherein said
injection valve has a first housing part with a stepped bore
respectively receiving said valve needle and said piston, and a
second housing part with a bore receiving a cylindrical part
therein in slidable sealtight relation, said cylindrical part
having a diameter greater than said valve needle and less than said
piston.
Description
This invention relates to an injection system. More particularly,
this invention relates to a fuel injection system for a diesel
engine.
It has been known in fuel injection systems for diesel engines to
use hydraulically controlled injection valves. In such instances,
the injection operation, i.e. the opening and closing of the valve,
is controlled by the fuel at the injection pressure. However, with
present day high fuel pressures of 1,000 atmospheres and above, the
control line in which the full fuel pressure and a much lower
pressure have been operative alternately has been subjected to
considerable stress.
Accordingly, it is an object of this invention to provide an
injection system which is subjected to a minimum of stress.
It is another object of the invention to provide an efficient
high-pressure fuel injection system.
It is another object of the invention to utilize a low pressure to
control the injection operation of an injection system.
Briefly, the invention provides an injection system for a diesel
engine which relies on the case of a low pressure to operate the
system while utilizing a fuel at high pressure. The system includes
an injection valve which is constructed with a valve seat, a valve
needle for seating on the valve seat and a piston connected to the
valve needle, a fuel duct which conveys fuel at a high pressure to
a space in front of the valve seat and a space in front of the
piston, and a control means which conveys a pressurized control
pressure medium of low pressure to a chamber to the rear of the
piston.
The piston in the injection valve is guided with a stepped bore
located in a first housing part of the valve in a sealtight manner
so as to divide the stepped part of the bore into two chambers, one
of which communicates with the control means while the other
communicates to a low-pressure space, for example, at atmospheric
pressure.
The fuel duct also cooperates with a second housing part of the
injection valve which has a bore receiving a cylindrical part in
slidable sealtight manner. The cylindrical part is disposed to abut
against the piston in the first housing part and is pressed against
the piston by the fuel pressure which is transmitted to a space in
front of the cylindrical part. The diameter of the cylindrical part
is greater than the needle valve and thus a differential pressure
is imposed on the needle valve by the fuel so as to seat the needle
valve on the valve seat. The diameter of the cylindrical part is,
however, less than the diameter of the piston such that when the
control means transmits a pressure to the chamber to the rear of
the piston sufficient to overcome the differential pressure, the
piston will move away from the valve seat. At the same time, due to
the connection between the needle valve and piston, the needle
valve will unseat from the valve seat causing injection of the
fuel.
In order to synchronize the transmittal of the pulse of pressure
necessary to cause opening of the valve, the control means can
utilize a rotary valve which has a duct for the supply of pressure
medium and at least one cylindrical control face and a bush which
surrounds the control face and contains a duct to receive the
pressure medium therefrom. The bush is further adjustably mounted
axially and circumferentially of the rotary valve.
These and other objects and advantages of the invention will become
more apparent from the following detailed description and appended
claims taken in conjunction with the accompanying drawings in
which:
FIG. 1 diagrammatically illustrates an injection system according
to the invention; and
FIG. 2 illustrates a developed view of the control face of the
rotary valve of the control means.
Referring to FIG. 1, a fuel injection valve 1 of a diesel engine is
connected to a fuel reservoir 2 which is in turn connected via a
fuel pipe 3 to a fuel pump 4 which delivers the fuel from a
suitable source, such as a tank, at a pressure required for
injection, e.g. 1,000 atmospheres. The injection valve 1 is also
connected by a control line 5 to a control valve 6 which receives a
hydraulic pressure medium--which is also fuel in this case--via a
pipe 8 from a pump 7. The pipe 8 may in this case be connected to
the same source of fuel as the pipe 3.
The injection valve 1 comprises a first housing part 10 formed in
known manner with jet bores 11. A valve seat 12 is formed in front
of the bores 11 and cooperates with a corresponding seat surface of
a valve needle 13. The valve needle 13 is guided in sealing-tight
relationship in a cylindrical bore 14 of the housing part 10 which
communicates with a larger bore 15 in the housing part 10. The bore
15 contains a piston 16 which is also guided in sealing-tight
relationship and which is rigidly connected to the valve needle 13
and may, for example, be integral therewith. The bore 15 thus forms
a cylinder for the piston 16 which in turn divides the bore into
two chambers 17, 18. One cylinder chamber 17 is connected to the
control line 5 by a duct 20 formed in the valve 1 while the other
cylinder chamber 18 communicates permanently with the external
atmosphere via a duct 21 shown in broken lines.
A cylinder part 22 is located above the piston 16 and is guided in
sealing-tight relationship in a bore 23 formed in a second housing
part 24. The cylindrical part 22 is supported against the piston
16, there being a space 25 above the part 22 in the bore 23. In the
valve 1, the space 25 communicates with a duct 26 connected to the
fuel pipe 3. The duct 26 also leads into the bottom zone of the
valve and into a cavity 27 in front of the valve seat 12.
The control member 6 contains a rotary valve 30 constructed in the
form of a shaft and connected via a drive (not shown) to the engine
crankshaft which drives the valve 30 accordingly. In a four-stroke
engine, the drive occurs, for example, at half the crankshaft speed
while in a two-stroke engine the drive occurs at the full engine
speed. The rotary valve 30 is provided with an axial bore 31
connected to the delivery line 8 of the pump 7. The pressure in
this line 8 may vary, for example, in the region of 200
atmospheres. The rotary valve 30 is also provided with a
cylindrical control surface 32 (shown in developed form in FIG. 2).
The control surface contains a substantially triangular recess 33
connected by a radial duct 34 to the bore 31 so as to be
permanently subjected to the pressure of the pump 7. Adjacent the
recess 33 and slightly spaced therefrom as shown, is a recess 35
which extends over the remainder of the periphery of the valve 30
and which is connected to atmosphere via a duct 36.
The control surface 32 forming the control plate of the valve 30 is
guided in sealing-tight relationship in a bush 37 provided with a
duct 38 leading to the exterior. The bush 37 is disposed in a valve
housing 40 having a duct 41 which is connected to the duct 38 and
to which the control line 5 is connected. Control members 42 and
43, which comprise gearwheels connected to levers and which mesh
with teeth extending circumferentially and longitudinally on the
bush 37 allow the bush 37 to be adjusted in these directions upon
manipulation of the levers.
The control valve 30 is further mounted in the valve housing 40 in
a bearing 44 which is lubricated with the pressure medium via a
bore 45.
As will be apparent from the drawing, the diameter D1 of the valve
needle 13 is smaller than the diameter D2 of the cylindrical part
22 which is in turn smaller than the diameter D3 of the piston 16.
Thus, if the control valve 1 is subjected only to the fuel
pressure, the valve needle 13 is pressed against the seat 12 by the
difference in the pressures operative on the part 22 in the space
25 and on the valve 13 in the space 27. Access of fuel to the jet
bores 11 and thus to the cylinder chamber is closed. As soon as the
hydraulic pressure operative in the cylinder chamber 17 is such as
to be sufficient to lift the valve needle against this pressure
difference, the valve 1 is opened and the fuel is injected from the
reservoir 2 into the engine combustion chamber via the jets 11.
This injection process continues as long as the control pressure is
operative in the cylinder chamber 17.
In order to vary the pressure in the cylinder chamber 17, the valve
30 of the control member 6 is rotated by the drive (not shown) so
that the duct 38 of the bush 37 which is in communication with duct
41 is alternatively brought into communication with recess 33 and
recess 35. That is, while the duct 38 is in communication with
recess 33, the pressure of line 8 is transmitted via control line 5
into the cylinder chamber 17 so that the piston 16 is lifted upon
the pressure becoming greater than the pressure differential caused
by the fuel pressure. Upon continued rotation of the rotary valve
30, recess 35 comes into communication with the duct 38 so that the
line pressure in line 8 is cut off from the control line 5. The
pressure in cylinder chamber 17 then drops off and, as the piston
16 moves down, the pressure medium is exhausted through duct 21 as
well as duct 36. Depending upon the axial adjustment of the bush
37, the communication between the duct 38 and recess 34 can last
for a longer or shorter period, owing to the triangular shape of
the recess 33. Thus, the duration of the injection operation and
hence the amount of fuel injected can be influenced. Control of the
amount of fuel is thus effected by the control member 43. Rotation
of the bush 37 with respect to the valve 30 by means of the control
member 42 alters the beginning and end of the injection
process.
The invention thus provides an injection system which is very
simple and very compact in construction and which is made with a
minimum number of conduits so that there is a minimum of leakage
losses.
It is noted that the control means can be used with injection
valves of a number of cylinders. It is only necessary for the
rotary valve to be provided with an appropriate number of
cylindrical control surfaces and for the appropriate number of
bushes to be provided.
* * * * *