Information
-
Patent Grant
-
6811105
-
Patent Number
6,811,105
-
Date Filed
Friday, November 1, 200222 years ago
-
Date Issued
Tuesday, November 2, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 239 5332
- 239 5333
- 239 5337
- 239 5338
- 239 5339
- 239 53312
- 239 5851
- 239 5852
- 239 5853
- 239 5854
- 239 5855
- 251 127
- 251 12915
- 251 12921
-
International Classifications
- F02M5900
- F02M6100
- B05B130
-
Abstract
In a fuel injection nozzle, a nozzle body is provided inside with a guide hole having a second guide portion (cylindrical hole) for slidably holding a guide shaft of a needle and a seat surface axially below the second guide portion, with first injection bores opened to the seat surface and with second injection bores opened to an inner circumference of the second portion. The needle is provided at an end thereof with a circular seat contact coming in contact with the seat surface axially above the first injection bores and inside the guide shaft with a fuel passage through which fuel is supplied to a position axially above the seat contact. With the construction mentioned above, as the second guide portion is formed axially above the sack chamber and inner diameter thereof is larger than that of the sack chamber, the second guide portion is more easily formed at lower cost.
Description
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority of Japanese Patent Applications No. 2001-351182 filed on Nov. 16, 2001 and No. 2002-149318 filed on May 23, 2002, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel injection nozzle in which a needle slidably fitted to a guide hole of a nozzle body stepwise lifts for injecting fuel.
2. Description of the Prior Art
Conventionally, as disclosed in JP-U-63-51154, JP-A-5-321789 and so on, a fuel injection nozzle is known, in which stepwise lift of a needle causes injection bores arranged axially up and down to sequentially open for injecting fuel. A first conventional fuel injection nozzle disclosed in JP-U-63-51154 has first injection bores opened to a seat surface of a nozzle body and second injection bores opened to a sack chamber of the nozzle body. A seat contact of a needle controls to open and close the first injection bores and a shaft tip of the needle inserted into the sack chamber controls to open and close the second injection bores.
A second conventional fuel injection nozzle disclosed in JP-A-5-321789 has fist and second injection bores provided axially at given intervals in a sack chamber of a nozzle body and a shaft tip of the needle inserted in the sack chamber controls to open and close both of the first and second injection bores.
However, the first conventional injection nozzle has a drawback that it is very difficult and costly to precisely form the sack chamber to secure better sliding inner surface of the sack chamber that comes in contact with the shaft tip of the needle without fuel leakage, since the sack chamber is positioned at the deepest bottom of the nozzle body and sack diameter thereof is relatively small.
Further, when fuel is supplied to the second injection bores after the first injection bores have been opened, fuel flows at high speed along the sliding inner surface of the sack chamber so that the sliding inner surface tends to be worn out by foreign material contained in the fuel. Furthermore, as the sack chamber provided at a leading end of the nozzle body is exposed to high temperature combustion gas, hardness of the shaft tip of the needle is likely reduced so that the shaft tip is prone to wear. As a result, when the needle is at a position where the second injection bores are closed and only first injection bores are opened, fuel is likely to be injected into an engine combustion chamber from the second injection bores due to the fuel leakage along the sliding inner surface of the sack chamber that has been worn out, which results in increasing black smoke and hydrocarbon contained in exhausted combustion gas.
In the second conventional fuel injection nozzle, the sack diameter is relatively large since the first injection bores are positioned in the sack chamber and it is required to secure sufficient fuel flow passage area therein. Consequently, it is inevitable that seat diameter is relatively large and pressure receiving area of the needle on which fuel pressure acts tends to be relatively small, failing in securing sufficient valve opening force so that response characteristic of opening and closing the injection bores is poorer.
Further, it is very difficult and costly to precisely form the sliding inner surface of the sack chamber, similarly to the first conventional fuel injection nozzle.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a fuel injection nozzle for injecting high pressure fuel in which a nozzle body member is easily manufactured to limit inadequate fuel leakage so that emissions such as black smoke and hydrocarbon are reduced.
To achieve the above object, in the fuel injection device, a nozzle body member is provided inside with a guide hole having a conical inner circumferential wall in a vicinity of an end thereof and a cylindrical inner circumferential wall axially above the conical inner circumferential wall, with at least a first injection bore whose one end is opened to the conical inner circumferential wall and whose another end is opened to outside, and on an axially above side of the first injection bore with at least a second injection bore whose one end is opened to one of the conical and cylindrical circumferential walls and whose another end is opened to outside. A needle member is inserted into the guide hole and the needle member is provided in a vicinity of an end thereof with a circular seat contact coming in contact with the conical inner circumferential wall, on an axially above side of the seat contact with a guide shaft whose outer diameter is larger than that of the circular seat contact and which is slidably fitted to the cylindrical circumferential wall, and with a fuel passage extending inside the guide shaft for introducing fuel to the first and second injection bores.
With the fuel injection nozzle mentioned above, when the needle member does not lift, the circular seat contact is in contact with the conical inner circumferential wall and the fuel passage does not communicate with both the first and second injection bores, when the needle member shows a first lift, the circular seat contact moves in a direction of leaving the conical inner circumferential wall and the fuel passage communicates with the first injection bore through a clearance between the circular seat contact and the conical inner circumferential wall but the guide shaft interrupts communication between the fuel passage and the second injection bore, and, when the needle member shows a second lift, the circular seat contact further moves in a direction of leaving the conical inner circumferential wall and, in addition to the communication between the fuel passage and the first injection bore, the guide shaft allows the communication between the fuel passage and second injection bore.
According to the fuel injection nozzle mentioned above, as the cylindrical inner circumferential wall is formed axially above the position where the sack chamber of the conventional fuel injection nozzle is provided and inner diameter of the cylindrical inner circumferential wall is larger than that of the sack chamber, the cylindrical inner circumferential wall is more easily formed at lower cost, compared with the conventional fuel injection nozzle in which the tip of the guide shaft is inserted into the sack chamber.
It is preferable that the needle member is provided axially above the guide shaft with an upper small diameter portion and axially below the guide shaft with a lower small diameter portion and the fuel passage is a plurality of through-holes each axially penetrating from an upper end of the guide shaft radially outside the upper small diameter portion to a lower end thereof radially outside the lower small diameter portion and axially above the circular seat contact. Further, the one end of the first injection bore is arranged axially below a position where the circular seat contact comes in contact with the conical inner circumferential wall, and outer circumference of the guide shaft serves, when the needle member does not lift or shows the first lift, to close the one end of the second injection bore and, when the needle member shows the second lift, to open the one end of the second injection bore.
Preferably, the guide shaft is provided at the lower end thereof radially outside the lower small diameter portion with a guide shaft ring groove to which the through-holes are opened so that the lower end circumference of the guide shaft radially outside the guide shaft ring groove constitutes a thin thickness wall. Accordingly, when the needle member does not lift or shows the first lift and the guide shaft ring groove is filled with high pressure fuel, the thin thickness wall of the lower end of the guide shaft expands radially outward so that the guide shaft fluid-tightly closes the one end of the second injection bore and suppresses fuel leakage from the second injection bore.
As an alternative, the fuel passage may has a lateral hole radially extending in the guide shaft at a position axially above an upper end of the cylindrical inner circumferential wall and a vertical hole whose one end is opened to the lateral hole, which axially extends through a center of the guide shaft and whose another end is opened to a lower end of the needle member axially below the circular seat contact. Further, the end of the first injection bore is arranged axially above a position where the circular seat contact comes in contact with the conical inner circumferential wall, and outer circumference of the guide shaft serves, when the needle member does not lift or shows the first lift, to close the one end of the second injection bore and, when the needle member shows the second lift, to open the one end of the second injection bore.
Further, it is preferable that the nozzle body member comprises a nozzle body and a ring shaped guide member whose outer circumference is press fitted into an inner circumference of the nozzle body. The ring shaped guide member has the cylindrical inner circumferential wall from which the second injection bore extends via both insides of the ring shaped guide member and the nozzle body to outside of the nozzle body. Since the cylindrical inner circumferential wall is formed in the ring shaped guide member that is a body separated from the nozzle body, the cylindrical inner circumferential wall can be more easily and precisely manufactured.
Moreover, it is preferable that both of the nozzle body and the ring shaped guide member have positioning portions with reference to which relative circumferential position between the nozzle body and the ring shaped guide member is defined. The respective positioning portions serve to secure an accurate relative circumferential position between the nozzle body and the ring shaped guide member, when the ring shaped guide member is formed separately from and, then, is press fitted into the nozzle body.
Furthermore, as an alternative, the needle member may have an outer needle provided inside with a cylindrical through-hole and in a vicinity of an end thereof with another circular seat contact coming in contact with the conical inner circumferential wall, and an inner needle slidably fitted to the cylindrical through-hole. The outer needle constitutes the guide shaft and the inner needle has the circular seat contact and the fuel passage. With this construction, when the needle member does not lift, both the circular and another circular seat contacts are in contact with the conical inner circumferential wall, when the needle member shows the first lift, only the inner needle moves and the outer needle does not move, and, when the needle member shows the second lift, the outer needle moves together with the inner needle.
Preferably, the fuel passage has a lateral hole radially extending in the inner needle at a position axially above an upper end of the outer needle and a vertical hole whose one end is opened to the lateral hole, which axially extends through a center of the inner needle and whose another end is opened to a lower end of the inner needle axially below the circular seat contact. Further, the one end of the first injection bore is arranged axially above a position where the circular seat contact comes in contact with the conical inner circumferential wall and axially below a position where the another circular seat contact comes in contact with the conical inner circumferential wall, the one end of the second injection bore is arranged at the conical inner circumferential wall axially above the position where the another circular seat contact comes in contact with the conical inner circumferential wall, and, when the needle member shows the first lift, the fuel passage communicates only with the first injection bore through the clearance between the circular seat contact and the conical inner circumferential wall and, when the needle member shows the second lift, the fuel passage communicates with the second injection bore through a clearance between the another circular seat contact and the conical inner circumferential wall.
Preferably, the inner and outer needles are provided with lift force transmitting means through which a lift force is transmitted from the inner needle to the outer needle at least when the needle member shows the second lift.
Further, it is preferable that at least one of the outer circumference of the guide shaft and the cylindrical inner circumferential wall is provided axially above the second injection bore with a ring shaped collection groove and the nozzle body member is provided with a collection passage whose one end communicates with the collection groove and whose another end communicates with a low pressure source, whereby the high pressure fuel entering a clearance between the outer circumference of the guide shaft and the cylindrical inner circumferential wall is returned through the collection groove and the collection passage to the low pressure source.
The collection groove serves not only to promote fuel lubrication in the clearance between the outer circumference of the guide shaft and the cylindrical inner circumferential wall is promoted but also to suppress fuel leakage through the second injection bore when the needle member does not lift or shows the first lift.
In case of the fuel injection nozzle having the inner and outer needles mentioned above, it is preferable that the outer needle is further provided with a radial through-hole whose one end communicates with the ring shaped collection groove when the needle member does not lift and the inner needle is provided on outer circumference thereof with a ring groove coming in communication with another end of the radial through-hole when the needle member shows the first lift. With the construction mentioned above, the high pressure fuel entering a clearance between the outer circumference of the outer needle and the cylindrical inner circumferential wall is returned through the collection groove and the collection passage to the low pressure source and the high pressure fuel entering a clearance between an outer circumference of the inner needle and an inner circumference of the outer needle is returned through the ring groove, the radial through-hole, the collection groove and the collection passage to the low pressure source.
Since the inner needle has the ring groove, high pressure fuel entering the clearance between the inner and outer needles is stored in the ring groove when the needle member does not lift so that not only fuel lubrication in the clearance between the inner and outer needles is promoted, but also fuel leakage through the first injection bore is suppressed.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention will be appreciated, as well as methods of operation and the function of the related parts, from a study of the following detailed description, the appended claims, and the drawings, all of which form a part of this application. In the drawings:
FIG. 1
is a cross sectional entire view of a fuel injection nozzle according to a first embodiment of the present invention;
FIG. 2
is a cross sectional view of an injector incorporating the fuel injection nozzle of
FIG. 1
;
FIG. 3
is a partly enlarged cross sectional view of the fuel injection nozzle of
FIG. 1
;
FIG. 4
is a partly enlarged cross sectional view of a fuel injection nozzle according to a second embodiment;
FIG. 5
is a partly enlarged cross sectional view of a fuel injection nozzle according to a third embodiment;
FIG. 6
is a partly enlarged cross sectional view of a fuel injection nozzle according to a fourth embodiment;
FIG. 7
is a partly enlarged cross sectional view of a fuel injection nozzle according to a fifth embodiment;
FIG. 8
is a partly enlarged cross sectional view of a fuel injection nozzle according to a sixth embodiment;
FIG. 9
is a cross sectional entire view of the fuel injection nozzle according to the sixth embodiment;
FIG. 10
is a cross sectional entire view of a fuel injection nozzle according to a seventh embodiment; and
FIG. 11
is a partly enlarged semi-cross sectional view of the fuel injection nozzle of FIG.
10
.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention are described with reference to drawings.
(First Embodiment)
FIG. 1
shows a cross sectional entire view of a fuel injection nozzle according to a first embodiment.
FIG. 2
shows a cross sectional entire view of an injector incorporating the fuel injection nozzle of FIG.
1
.
FIG. 3
shows an enlarged cross sectional view of an end portion of the fuel injection nozzle of FIG.
1
.
A fuel injection nozzle
1
(hereinafter called a nozzle
1
) according to the first embodiment is applicable typically to an injector
2
for diesel engines and, as shown in
FIG. 2
, is composed of a nozzle body (nozzle body member)
3
and a needle (needle member)
4
accommodated in the nozzle body
3
. The nozzle
1
is fixed to a lower end of an injector body
5
by a retaining nut
6
.
In the injector
2
, a piston
8
is slidably fitted into a through-hole
7
extending to axially pass through the injector body
5
. An electromagnetic actuator is fixed via a piece of plate
9
and two pieces of shims
10
to an upper end of the injector body
5
by a nut
11
.
The piston
8
is provided at an upper end thereof with a polygon shaped cut portion
8
a
. Space is provided between an upper end of the cutting portion
8
a
and the plate
9
to set a maximum lift amount (h
1
+h
2
) of the needle
4
.
A fuel connector
13
,in which a fuel filter
12
is housed, is attached to the injector body
5
. High pressure fuel is supplied to the fuel connector
13
from a common rail (not shown). The fuel connector
13
is provided inside with a high pressure passage
13
a
communicating with the through-hole
7
so that high pressure fuel filtered by the fuel filter
12
is supplied to the through-hole
7
via the high pressure passage
13
a.
The through-hole
7
is provided at a lower end thereof with a spring chamber
15
in which a second spring
14
is accommodated. The spring chamber
15
is used as a part of a fuel passage.
The electromagnetic actuator is composed of a coil
16
to which control current is applied via a drive circuit (EDU) from an electric control device (ECU), an armature
17
connected to and movable together with the piston
8
, a core
18
axially opposed to the armature
17
with air gap therebetween and a first spring
19
urging the armature
17
downward in FIG.
2
. Upon energizing the coil
16
, the armature
17
is attracted upward so that the piston
8
is driven.
The air gap between the armature
17
and the core
18
is set to be slightly larger than the maximum lift amount (h
1
+h
2
) of the needle
4
.
The nozzle body
3
is provided with a guide hole
20
into which the needle
4
is inserted, a fuel passage
21
and fuel injection bores (first injection bores
23
and second injection bores
24
).
Upper and lower ends of the guide hole
20
have first and second guide portions (cylindrical holes)
20
a
and
20
b
which support slidably the needle
4
, respectively. A conical shaped seat surface
25
is provided beneath the lower end of the second guide portion
20
b
and a sack chamber
26
is provided at a tip of the seat surface
25
. Inner diameter of the second guide portion
20
b
is smaller than that of the first guide portion
20
a.
A fuel sump
22
, whose diameter is partly expanded on a way of the guide hole
20
, communicates with the spring chamber
15
through a fuel passage
21
(refer to
FIG. 2
) for introducing high pressure fuel from the spring chamber
15
to the fuel sump
22
.
The fuel injection bores are composed of the first injection bores
23
opened to the seat surface
25
and the second injection bores
24
opened to a cylindrical inner circumferential surface of the second guide portion
20
b
. The respective first and second injection bores
23
and
24
are arranged circumferentially at regular intervals or irregular intervals in consideration of relationship between shape of an engine combustion chamber and intake air flow.
The needle
4
is provided at an upper end thereof with a first guide shaft
27
slidably supported by the first guide portion
20
a
and at a lower end thereof with a second guide shaft
28
sidably supported by the second guide portion
20
b
. As shown in
FIG. 4
, the needle
4
is provided at a lower end thereof with an upper conical surface and a lower conical surface whose conical angle is larger than that of the upper conical surface. A boundary line between the upper and lower conical surfaces constitutes a seat contact
29
to be seated on the seat surface
25
at a valve closing time.
The needle
4
is provided on upper and lower sides of the second guide shaft
28
, respectively, with an upper side small diameter portion
30
and a lower side small diameter portion
31
whose each diameter is smaller than that of the second guide shaft
28
. The needle
4
is further provided radially outside the upper and lower small diameter portions
30
and
31
with through-holes
32
penetrating axially from an upper end surface of the second guide shaft
28
to a lower end surface thereof. The through-holes
32
are fuel passages for delivering fuel from an upstream side of the second guide shaft
28
to a downstream side of the second guide shaft
28
(an oil sump
33
formed at outer circumference of the lower small diameter portion
31
). The through-holes
32
are formed typically at four positions of the second guide shaft
28
excluding pillar portions
34
thereof and being spaced circumferentially. Each cross section of the through-holes
32
perpendicular to an axis of the second guide shaft
28
is formed in circular shape. The second guide shaft
28
is provided at the lower end with a ring shaped groove
32
a
to which each end of the through-holes
32
on a side of the lower small diameter portion
31
is opened so that a thin thickness circumferential wall
28
a
of the second guide shaft
28
is formed around the ring shaped groove
32
a.
The seat contact
29
controls to open and close the first injection bores
23
and the second guide shaft
28
controls to open and close the second injection bores
24
. That is, the first injection bores
23
are opened on a downstream side of the seat surface
25
with respect to a position where the seat contact
29
is seated on the seat surface
25
at a valve closing time.
As shown in
FIG. 3
, the second injection bores
24
are arranged at positions where openings of the second injection bores
24
are closed by the thin thickness circumferential wall
28
a
at a valve closing time. The thin thickness circumferential wall
28
a
is resiliently deformable and expanded radially outward, when the thin thickness circumferential wall
28
a
receives fuel pressure, so that a clearance between the second guide shaft
28
and the second guide portion
20
is fluid-tightly blocked.
As shown in
FIG. 2
, the needle
4
has a pole shaped projection
4
a
projecting upward from the first guide shaft
27
. A spherical portion
4
b
provided at an upper end of the pole shaped projection
4
a
is rotatably fitted to a spherical recess provided at a lower end of the piston
8
so that the needle
4
is connected to and movable up and down together with the piston
8
. A space is provided between an upper end of the first guide shaft
27
and a plate
35
disposed in the spring room
15
to set a first lift amount (h
1
) of the needle
4
in a state that the seat contact
29
is seated on the seat surface
25
.
An operation of the nozzle
1
is described below.
Fuel supplied to the injector
2
from the common rail is introduced after being filtered by the fuel filter
12
of the fuel connector
13
into the through-hole
7
via the high pressure passage
13
a
and, then, supplied to the nozzle
1
via the spring chamber
15
.
In the nozzle
1
, the fuel is supplied to the guide hole
20
(ring shaped space formed around the needle
4
) from the fuel passage
21
of the nozzle body
3
and the fuel sump
22
and, then, to the oil sump
33
via the through-holes
32
of the second guide shaft
28
so that space between the oil sump
33
and the seat contact
29
in contact with the seat surface
25
is filled with the fuel.
At this time, the needle
4
receives a force corresponding to fuel pressure multiplied by a cross sectional area of the seat contact
29
. This force urges the needle
4
toward the seat surface
25
of the nozzle body
3
. In addition to this force, preset load of the first spring
19
incorporated in the electromagnetic actuator biases the needle
4
so that the needle
4
is pushed downward to keep a valve closing state.
When first value of current is applied to the coil
16
, magnetic force is induced between the core
18
and the armature
17
so that the armature
17
is attracted toward the core
18
with attracting force which exceeds a sum of forces due to the preset load of the spring
19
and the fuel pressure urging the needle
4
in a valve closing direction. Accordingly, the armature
17
moves upward together with the piston
8
and the needle
4
.
The first value of current does not induce the magnetic force which is sufficient enough to attract the armature
17
against preset load of the second spring
14
after the upper end of the needle
4
comes in contact with the plate
35
so that the needle
4
rests after having moved upward by the first lift amount (h
1
). As a result, the seat contact
29
of the needle
4
leaves the seat surface
25
so that the first injection bores
23
are opened to inject high pressure fuel therefrom. At this time, that is, in a first lift state, an injection rate as injection characteristic of the fuel injection nozzle
1
is low, since the outer circumference of the second guide shaft
28
(the thin thickness circumferential wall
28
a
closes the second injection bores
24
. When the diesel engine is under conditions of low/middle speed and low/middle load, the first lift state is applicable for realizing an optimum operation of the engine in which atomized combustible mixture of fuel and air is stratified to improve fuel consumption, exhaust emission and noises.
When second value of current is applied to the coil
16
, the force of attracting the armature
17
exceeds the preset load of the second spring
14
so that the needle
4
further moves upward until the upper end of the piston
8
comes in contact with the plate
9
to achieve the maximum lift amount (h
1
+h
2
). At this time, that is, in second lift state, the injection rate as injection characteristic of the fuel injection nozzle
1
is high, since the second guide shaft
28
is at a position where the second injection bores are opened and high pressure fuel is injected from not only from the first injection bores
23
but also from the second injection bores
24
. The second lift state is applicable, when the engine is under conditions of high load, for realizing widely diffused atomization whose destination distance is longer to secure optimum combustion.
When current supply to the coil
16
stops, the electromagnetic force for attracting the armature
17
extinguishes so that all of the armature
17
, the piston
8
and the needle
4
are pushed down by the biasing forces of the first and second springs
19
and
14
.
When the needle
4
is pushed down to a position corresponding to the first lift state, the biasing force of the second spring
14
does not act on the needle
4
and only the biasing force of the first spring
19
acts in a direction of pushing down the armature
17
. Accordingly, the seat contact
29
of the needle
4
comes in contact with and is pressed against the seat surface
25
due to the biasing force of the first spring
19
.
Though the first embodiment mentioned above is described as an example in which the nozzle
1
is controlled to achieve the second lift state (maximum lift state) successively after the first lift state is achieved, the nozzle
1
may be controlled to achieve only the first lift state or to achieve only the second lift state by skipping the first lift state.
In the nozzle
1
mentioned above, the second guide portion
20
b
, whose inner diameter is larger than the seat diameter, supports the second guide shaft
28
of the needle
4
. That is, the second guide portion
20
is arranged axially above the seat position where the seat contact
29
of the needle
4
comes in contact with the seat surface
25
. Since the second guide portion
20
b
is positioned axially above the sack chamber
26
and the inner diameter of the guide portion
20
b
is larger than that of the sack chamber
26
, the second guide portion
20
can be easily and precisely manufactured at lower cost, compared with the conventional nozzle in which the shaft end of the needle is inserted into and supported by the sack chamber.
Further, according to the present embodiment, the sack chamber
26
is provided as a relief for manufacturing the seat surface
25
and also as a relief for preventing the leading end of the needle
4
from being interfered with the nozzle body
3
at the valve closing time. Therefore, it is not necessary to manufacture precisely the sack chamber
26
since the sack chamber
26
is not used as the sliding portion that is required in the conventional sack chamber.
The needle
4
according to the present embodiment is provided inside the second guide shaft
28
with the through-holes
32
serving as the fuel passages, and at the lower end of the second guide shaft
28
with the ring shaped groove
32
and the thin thickness circumferential wall
28
a
. Pressure of fuel with which the through-holes
32
are filled serves to deform the thin thickness circumferential wall
28
a
radially outward so that the clearance between the outer circumference of the second guide shaft
28
and the inner circumference of the second guide portion
20
b
is blocked to completely close the second injection bores
24
opened to the second guide portion
20
b
, resulting in preventing fuel leakage from the second injection bores
24
.
At the valve opening time when the needle
4
moves upward, the thin thickness circumferential wall
28
a
is less deformed since fuel pressure in the oil sump
33
is lower so that sliding motion between the second guide portion
20
b
and the second guide shaft
28
a
is smoother. Further, at the valve closing time when the needle
4
moves downward, the sliding motion between the second guide portion
20
b
and the second guide shaft
28
a
is still smoother and does not harm the valve closing operation since the fuel is injected from the first and second injection bores
23
and
24
, flow speed of fuel passing through the through-holes
32
is higher and pressure of the fuel is lower.
(Second Embodiment)
FIG. 4
shows an enlarged cross sectional view of an end portion of a nozzle according to a second embodiment.
In a nozzle
1
according to the second embodiment, a diameter of the second guide shaft
28
is smaller than that of the first embodiment. The second guide shaft
28
is provided with a fuel passage
36
passing through an inside thereof and communicating with the sack chamber
26
, instead of the through-hole
32
of the first embodiment.
As shown in
FIG. 4
, an outer diameter of the second guide shaft
28
of the needle
4
is slightly larger than that of the lower side small diameter portion
31
.
The fuel passage
36
is composed of a plurality of lateral holes
36
a
circumferentially spaced and radially extending in the second guide shaft
28
at a position axially above an upper end of the second guide portion
20
b
in a valve closing state and a vertical hole
36
b
whose one end is opened to the lateral holes
36
a
, which axially extends through a center of the second guide shaft
28
and whose another end is opened to a lower end of the needle
4
axially below the seat contact
29
.
With the construction mentioned above, since fuel is supplied to the lower end of the needle
4
that is positioned axially below the seat contact
29
, fuel pressure is not applied to the oil sump
33
in a valve closing state so that fuel leakage from the second injection bores
24
is suppressed in the valve closing state.
Further, as the outer diameter of the second guide shaft
28
is smaller, the second injection bores
24
can be formed at lower position of the nozzle body
3
so that the nozzle
1
less protrudes into the combustion chamber of the engine. Further, Even if the seat diameter is smaller, sufficient valve opening force can be secured.
Moreover, since fuel flows from the lateral holes
36
a
trough the vertical hole
36
b
and the sack chamber
26
to the seat contact
29
, the axial end of the nozzle
1
is cooled down by the fuel so that strength deterioration of the nozzle
1
due to heat is prevented and the preheated fuel promotes fuel atomization.
(Third Embodiment)
FIG. 5
shows an enlarged cross sectional view of an end portion of a nozzle according to a third embodiment.
In a nozzle
1
according to the third embodiment, a ring shaped guide member
37
, which is provided separately from a nozzle body
3
a
, has a second guide portion
37
a
at inner circumference thereof and an outer circumference of the ring shaped guide member
37
is press fitted to the guide hole
20
of the nozzle body
3
a
. The ring shaped guide member
37
and the nozzle body
3
a
constitute the nozzle body member
3
.
The nozzle body
3
a
and the ring shaped guide member
37
have positioning portions
3
b
and
37
b
with reference to which relative circumferential position between the nozzle body
3
a
and the ring shaped guide member
37
is defined.
The ring shaped guide member
37
is provided a conical surface
37
in intimate and fluid-tight contact with the seat surface
25
of the nozzle body
3
a
and with through-holes
37
d
each communicating with the second injection bore
24
formed in the nozzle body
3
a
. The through-hole
37
d
is a part of the second injection bore
24
. The ring shaped guide member
37
may be provided on the inner circumference thereof (on the second guide portion
37
a
) with a ring groove
37
e
communicating with an inlet end of the through-hole
37
d
so that the ring groove
37
e
is opened and closed by the second guide shaft
28
and, further, on the outer circumference thereof with an enlarged portion
37
f
communicating with the second injection bore
24
formed in the nozzle body
3
a.
Since the second guide portion
37
a
is not provided in the nozzle body
3
a
but provided in the ring shaped guide member
37
separately formed from the nozzle body
3
a
, the second guide portion
37
a
, which is a cylindrical inner circumferential wall for supporting the second guide shaft
28
, can be easily and precisely manufactured.
Further, smaller inner diameter of the second guide portion
37
can be formed, since the ring shaped guide member
37
and the nozzle body
3
a
are separate bodies, so the outer diameter of the second guide shaft
28
is smaller than that of the second embodiment.
Moreover, the through-hole
37
can be formed at an angle different from that of the second injection bore
24
formed in the nozzle body
3
a
. The outlet end of the second injection bore
24
can be formed at a lower position of the nozzle body
3
a
, compared with that of the second embodiment. As a result, the nozzle
1
less protrudes into the combustion chamber of the engine, so strength deterioration of the nozzle body
3
a
due to heat is smaller.
Furthermore, the nozzle
1
according to the third embodiment can be formed by press fitting the ring shaped guide member
37
separately provided into the conventional nozzle body without newly designing the nozzle
1
.
(Fourth Embodiment)
FIG. 6
shows an enlarged cross sectional view of an end portion of a nozzle according to a fourth embodiment.
In addition to the construction of the nozzle
1
according to the first embodiment, a nozzle
1
according to the fourth embodiment has fuel collection means for collecting fuel flowed into a sliding clearance between the second guide shaft
28
of the needle
4
and the second guide portion
20
b.
The fuel collection means are composed of a collection groove
38
provided in the nozzle body
3
and a collection passage
39
.
The collection groove
38
is a ring shaped groove provided on an inner circumference of the second guide portion
20
b
and is positioned axially above the ends (inlet side) of the second injection bores
24
that are opened thereto. The collection groove
38
may be provided on an outer circumference of the second guide shaft
28
.
The collection passage
39
extends axially upward from the collection groove
38
to an upper end of the nozzle body
3
and communicates with a leakage passage (not shown) provided in the injector body
5
. The leakage passage is connected via a return pipe (not shown) to the fuel tank (low pressure source).
With the construction mentioned above, the collection groove
38
can collect high pressure fuel entering the sliding clearance between the second guide shaft
28
and the second guide portion
20
b
from an axial upper end side of the second guide shaft
28
before reaching the second injection bores
24
, which results in reducing fuel leakage from the second injection bores
24
at the valve closing time.
The fuel collected in the collection groove
38
is returned to the fuel tank via the collection passage
39
, the leakage passage and the return pipe. Further, high pressure fuel flowed into the clearance between the second guide shaft
28
and the second guide portion
20
b
serves to promote smooth slide of the second guide shaft
28
on the second guide portion
20
b.
(Fifth Embodiment)
FIG. 7
shows an enlarged cross sectional view of an end portion of a nozzle according to a fifth embodiment.
In addition to the construction of the nozzle
1
according to the second embodiment, a nozzle
1
according to the fifth embodiment has fuel collection means.
Similarly to the fourth embodiment, the fuel collection means are composed of a ring shaped collection groove
38
provided in the inner circumference of the second guide portion
20
b
or the outer circumference of the second guide shaft
28
and a collection passage
39
communicating with the collection groove
38
.
The fuel collection means according to the fifth embodiment has the same advantage as the fourth embodiment.
(Sixth Embodiment)
FIG. 8
shows an enlarged cross sectional view of an end portion of a nozzle according to a fifth embodiment.
FIG. 9
shows a cross sectional entire view of the nozzle of FIG.
8
.
In addition to the construction of the nozzle
1
according to the third embodiment, a nozzle
1
according to the sixth embodiment has fuel collection means, as shown in FIG.
8
. The fuel collection means are composed of a collection groove
38
and a collection hole
40
both provided in the guide member
37
and a collection passage
39
provided in the nozzle body
3
a.
The collection groove
38
is a ring shaped groove provided on an inner circumference of the second guide portion
37
a
and is positioned axially above the end (inlet side) of the communication hole
37
d
. The collection groove
38
may be provided on an outer circumference of the second guide shaft
28
.
The collection hole
40
communicating with the collection groove
38
penetrates the guide member
37
so as to reach the outer circumference thereof and to open to a space
41
provided at a bottom of the guide hole
20
.
As shown in
FIG. 9
, the collection passage
39
extends in an up and down direction along the guide hole
20
inside the nozzle body
3
. An end of the collection passage
39
communicates via the space
41
with the collection hole
40
and the other end thereof is opened to the axial upper end of the nozzle body
3
a.
With the construction mentioned above, the collection groove
38
can collect high pressure fuel entering the sliding clearance between the second guide shaft
28
and the second guide portion
37
a
from an axial upper end side of the second guide shaft
28
before reaching the second injection bores
24
, which results in reducing fuel leakage from the second injection bores
24
at the valve closing time. The fuel collected in the collection groove
38
is returned to the fuel tank via the collection hole
40
, the space
41
, the collection passage
39
, the leakage passage and the return pipe. Further, high pressure fuel flowed into the clearance between the second guide shaft
28
and the second guide portion
37
a
serves to promote smooth slide of the second guide shaft
28
on the second guide portion
37
a.
(Seventh Embodiment)
FIG. 10
shows a cross sectional entire view of a nozzle according to a seventh embodiment.
FIG. 11
is a semi-cross sectional view of the nozzle of FIG.
10
.
A nozzle
1
according to the seventh embodiment has a needle (needle member)
4
having dual construction for opening and closing injection bores (first and second injection bores
23
and
24
).
The needle
4
is composed of a cylindrical outer needle
42
(second needle
42
) for opening and closing the second injection bores
24
and an inner needle
43
(first needle
43
) slidably fitted into a hollow (
42
d
) of the second needle
42
for opening and closing the first injection bores
23
.
The second needle
42
, whose axial upper end is positioned at the fuel sump
22
, is slidably fitted into the guide hole
20
(cylindrical inner circumferential wall
20
b
) of the nozzle body
3
and, upon receiving fuel pressure of the fuel sump
22
, is operative to close the second fuel injection bores
24
. The second needle
42
is provided at an axial lower end thereof with an upper side conical surface
42
a
and a lower side conical surface
42
b
whose conical angle is different from and larger than that of the upper side conical surface
42
a
. An annular boundary between the conical surfaces
42
a
and
42
b
constitutes a seat contact
42
c
(second seat contact
42
c
) coming in contact with the seat surface
25
of the nozzle body
3
at the valve closing time of the second injection bores
24
(refer to FIG.
11
).
The first needle
43
is formed integrally with the first guide shaft
27
described in the first embodiment and provided at an axial end thereof with the seat contact (first seat contact
43
a
). The first seat contact
43
a
is constituted by an annular boundary between two conical surfaces whose conical angles are different, similarly to the second needle
42
.
The first needle
43
has a fuel passage
36
through which high pressure fuel is supplied from the fuel sump
22
to the seat surface
25
. The fuel passage
36
is composed of a lateral hole
43
c
radially extending in a middle diameter portion
43
b
of the first needle
43
at a position axially above an upper end of the second needle
42
and a vertical hole
43
d
whose one end is opened to the lateral hole
43
c
, which axially extends through a center of the first needle
43
and whose another end is opened to a lower end of the first needle axially below the circular seat contact
43
a.
Further, the nozzle
1
according to the seventh embodiment has fuel collection means for collecting fuel flowed from the fuel sump to a sliding clearance between the guide hole
20
and the second needle
42
and to a sliding clearance between the first and second needles
43
and
42
.
As shown in
FIG. 10
, the fuel collection means are composed of a collection groove
38
and a collection hole
44
both formed in the second needle
42
, a ring shaped collection groove
45
formed in the first needle
43
and a collection passage
39
formed in the nozzle body
3
.
The collection groove
38
of the second needle
42
is provided at a relatively upper part of the second needle
42
and formed in shape of a ring along an outer circumference of the second needle
42
.
The collection hole
44
is a through-hole which radially extends in the second needle
42
, whose one end communicates with the collection groove
38
and whose another end is opened to an inner circumference of the second needle
42
.
The collection groove
45
of the first needle
43
is a ring groove formed on and along the outer circumference of the first needle at a position where the collection groove
45
communicates with the collection hole
44
when the first needle shows a first lift to open the first injection bores
23
.
An end of the collection passage
39
is opened to the inner circumference of the guide hole
20
and communicates with the collection groove
38
of the second needle
42
. Another end of the collection passage
39
is opened to the axial upper end of the nozzle body
3
and communicates with a leakage passage (not shown). The collection passage
39
communicates with the collection groove
38
only when the second needle
42
closes the second injection bores
24
(when the second seat contact
42
c is seated on the seat surface
25
) and the communication between the collection passage
39
and the collection groove
38
is interrupted when the second needle
42
shows a lift to open the second injection bores
24
, that is, when the first needle
43
shows a second lift.
The leakage passage is formed in the injector body
5
and connected via a return pipe (not shown) to the fuel tank.
According to the fuel collection means mentioned above, high pressure fuel flowed from the fuel sump
22
to a sliding clearance between the guide hole
20
and the second needle
42
is collected in the collection groove
38
of the second needle
42
and returned to the fuel tank via the collection passage
39
, the leakage passage and the return pipe.
High pressure fuel flowed from the fuel sump
22
to a sliding clearance between the first and second needles
43
and
42
is collected in the collection groove
45
of the first needle
43
and returned to the fuel tank via the collection hole
44
, the collection groove
38
, the collection passage
39
, the leakage passage and the return pipe when the collection groove
45
communicates with the collection hole
44
at the first lift time of the first needle
43
.
According to the needle
4
having the dual construction, a pin
46
press fitted into the middle diameter portion
43
b
of the first needle
43
is coupled and co-works with a lift inducement hole
47
formed at an upper part of the second needle
42
in such a manner that, after the first needle
43
lifts (first lift) for opening the first injection bores
23
, the second needle
42
lifts together with the first needle
43
(second lift) for opening the second injection bores
24
.
The pin
46
is coupled with the lift inducement hole
47
with a slight clearance between the pin
46
and a lower end of the lift inducement hole
47
when the first and second needles
43
and
42
do not lift and are in valve closing states so that the first needle
43
may close the first injection bore
23
without fail and with a slight clearance between the pin
46
and an upper end of the lift inducement hole
47
when the first needle
43
is in valve opening state and the second needle
42
is in valve closing state (first lift time) so that the second needle
42
may close the second injection bores
24
without fail. The pin
46
and the lift inducement hole
47
constitute lift force transmitting means.
Next, an operation of the nozzle
1
according to the seventh embodiment is described.
The lift control of the needle
4
is performed by changing a value of current applied to the coil
16
(refer to
FIG. 2
) of the electromagnetic actuator, similarly to the first embodiment. That is, at the first lift time, a first value of current is applied to the coil
16
so that the first needle
43
moves upward by the first lift amount (refer to the first embodiment) and, then, rests. At this time, the pin
46
press fitted to the middle diameter portion
43
b
of the first needle
43
moves to a position just before contacting the upper end of the lift inducement hole
47
formed in the second needle
42
. Consequently, the first seat contact
43
a
leaves the seat surface
25
so that only the first injection bores
23
are opened for injecting fuel.
At the second lift time, a second value of current is applied to the coil
16
so that the first needle
43
moves upward up to the maximum lift amount (refer to the first embodiment). At this time, the pin
46
press fitted to the middle diameter portion
43
b
of the first needle
43
comes in contact with the upper end of the lift inducement hole
47
formed in the second needle
42
and pushes upward the second needle
42
so that the second needle
42
lifts together with the first needle
43
. Consequently, the second seat contact
42
c
leaves the seat surface to open the second injection bores
24
so that fuel is injected not only from the first injection bores
23
but also from the second injection bores
24
.
Then, when the current supply to the coil
16
stops, the first needle
43
is pushed in a valve closing direction by the biasing forces of the first and second springs
19
and
14
(refer to FIG.
2
). On a way of the movement of the first needle
43
in a valve closing direction, the second needle
42
is pushed downward together with the first needle
43
since the pin
46
presses the lower end of the lift inducement hole
47
. As a result, the first seat contact of the first needle
43
is seated on the seat surface
25
to close the first injection bores
23
so that fuel supply to the lower side of the conical surfaces
42
a
and
42
b
of the second needle
42
is blocked. Subsequently, the second needle
42
is further pushed downward by fuel pressure of the fuel sump
22
so that fuel on the lower side of the conical surfaces
42
a
and
42
b
is injected under high pressure from the fuel injection bores
24
. When the second contact
42
c
is seated on the seat surface
25
, the second injection bores
24
are closed.
In the nozzle according to the seventh embodiment, the first needle
43
for opening and closing the first injection bores
23
is held by the second needle
42
for opening and closing the second injection bores
24
and the second needle
42
is slidably fitted to the guide hole
20
of the nozzle body
3
. With this construction, both first and second injection bores
23
and
24
can be opened to the seat surface
25
of the nozzle body
3
so that it is not necessary to provide the injection bores in the sack chamber
26
and to precisely form the sack chamber
26
.
As the inner diameter of the guide hole
20
for slidably holding the second needle
42
is larger than the seat diameter (a diameter of annular contact between the second seat contact
42
c
and the seat surface
25
), manufacturing work of the guide hole is relatively easy.
Further, since the second needle
42
is moved by the first needle
43
and the fuel pressure of the fuel sump
22
, two step injection bore opening and closing control is performed without providing additional means such as springs.
Furthermore, in the nozzle
1
of the present embodiment, since the first and injection bores
23
and
24
are opened and closed by the first and second needles
43
and
42
, respectively, fuel flowing from the fuel sump and entering the sliding clearance between the first and second needles
43
and
42
does not leak from the second fuel injection bores
24
at a valve closing time of the second injection bores
24
.
Moreover, as the second needle
42
has a length to an extent that the axial end thereof reaches the fuel sump
22
, the collection groove
38
is positioned at a relatively upper part of the second needle
42
and the collection groove
45
is also positioned at an upper part of the first needle
43
. As a result, fuel entering the sliding clearance between the first and second needles
43
and
42
and the sliding clearance between the guide hole
20
and the second needle
42
from the fuel sump
22
is less leaked from the first and second injection bores
23
and
24
.
Claims
- 1. A fuel injection nozzle for injecting high pressure fuel comprising:a nozzle body member provided inside with a guide hole having a conical inner circumferential wall in a vicinity of an end thereof and a cylindrical inner circumferential wall axially above the conical inner circumferential wall, with at least a first injection bore whose one end is opened to the conical inner circumferential wall and whose another end is opened to outside, and on an axially above side of the first injection bore with at least a second injection bore whose one end is opened to one of the conical and cylindrical circumferential walls and whose another end being opened to outside; and a needle member inserted into the guide hole, the needle member being provided in a vicinity of an end thereof with a circular seat contact coming in contact with the conical inner circumferential wall, on an axially above side of the seat contact with a guide shaft whose outer diameter is larger than that of the circular seat contact and which is slidably fitted to the cylindrical circumferential wall, and with a fuel passage extending inside the guide shaft for introducing fuel to the first and second injection bores, wherein, when the needle member does not lift, the circular seat contact is in contact with the conical inner circumferential wall and the fuel passage does not communicate with both the first and second injection bores, when the needle member shows a first lift, the circular seat contact moves in a direction of leaving the conical inner circumferential wall and the fuel passage communicates with the first injection bore through a clearance between the circular seat contact and the conical inner circumferential wall but the guide shaft interrupts communication between the fuel passage and the second injection bore, and, when the needle member shows a second lift, the circular seat contact further moves in a direction of leaving the conical inner circumferential wall and, in addition to the communication between the fuel passage and the first injection bore, the guide shaft allows the communication between the fuel passage and second injection bore.
- 2. A fuel injection nozzle according to claim 1, wherein the needle member is provided axially above the guide shaft with an upper small diameter portion and axially below the guide shaft with a lower small diameter portion and the fuel passage is at least a through-hole axially penetrating from an upper end of the guide shaft radially outside the upper small diameter portion to a lower end thereof radially outside the lower small diameter portion and axially above the circular seat contact and, further, wherein the one end of the first injection bore is arranged axially below a position where the circular seat contact comes in contact with the conical inner circumferential wall, and outer circumference of the guide shaft serves, when the needle member does not lift or shows the first lift, to close the one end of the second injection bore and, when the needle member shows the second lift, to open the one end of the second injection bore.
- 3. A fuel injection nozzle according to claim 2, wherein the guide shaft is provided at the lower end thereof radially outside the lower small diameter portion with a guide shaft ring groove to which the through-hole is opened so that the lower end circumference of the guide shaft radially outside the guide shaft ring groove constitutes a thin thickness wall expanding radially outward when the needle member does not lift or shows the first lift so that the guide shaft fluid-tightly closes the one end of the second injection bore and suppresses fuel leakage from the second injection bore.
- 4. A fuel injection nozzle according to claim 1, wherein the fuel passage comprises a lateral hole radially extending in the guide shaft at a position axially above an upper end of the cylindrical inner circumferential wall and a vertical hole whose one end is opened to the lateral hole, which axially extends through a center of the guide shaft and whose another end is opened to a lower end of the needle member axially below the circular seat contact and, further, wherein the end of the first injection bore is arranged axially above a position where the circular seat contact comes in contact with the conical inner circumferential wall, and outer circumference of the guide shaft serves, when the needle member does not lift or shows the first lift, to close the one end of the second injection bore and, when the needle member shows the second lift, to open the one end of the second injection bore.
- 5. A fuel injection nozzle according to claim 4, wherein the nozzle body member comprises a nozzle body and a ring shaped guide member whose outer circumference is press fitted into an inner circumference of the nozzle body, the ring shaped guide member having the cylindrical inner circumferential wall from which the second injection bore extends via both insides of the ring shaped guide member and the nozzle body to outside of the nozzle body.
- 6. A fuel injection nozzle according to claim 5, wherein both of the nozzle body and the ring shaped guide member have positioning portions with reference to which relative circumferential position between the nozzle body and the ring shaped guide member is defined.
- 7. A fuel injection nozzle according to claim 5, wherein at least one of the outer circumference of the guide shaft and the cylindrical inner circumferential wall of the ring shaped guide member is provided axially above the second injection bore with a ring shaped collection groove and each of the ring shaped guide member and the nozzle body is provided with a collection passage, one end of the collection passage of the ring shaped guide member communicating with the collection passage and another end thereof communicating with an end of the collection passage of the nozzle body and another end of the collection groove of the nozzle body communicating with a low pressure source, whereby the high pressure fuel entering a clearance between the outer circumference of the guide shaft and the cylindrical inner circumferential wall of the ring shaped guide member is returned through the collection groove and the collection passages of the ring shaped guide member and the nozzle body to the low pressure source.
- 8. A fuel injection nozzle according to claim 1, wherein the needle member comprises an outer needle provided inside with a cylindrical through-hole and in a vicinity of an end thereof with another circular seat contact coming in contact with the conical inner circumferential wall, and an inner needle slidably fitted to the cylindrical through-hole, the outer needle constituting the guide shaft and the inner needle having the circular seat contact and the fuel passage, and, further, wherein, when the needle member does not lift, both the circular and another circular seat contacts are in contact with the conical inner circumferential wall, when the needle member shows the first lift, only the inner needle moves and the outer needle does not move, and, when the needle member shows the second lift, the outer needle moves together with the inner needle.
- 9. A fuel injection nozzle according to claim 8, wherein the fuel passage comprises a lateral hole radially extending in the inner needle at a position axially above an upper end of the outer needle and a vertical hole whose one end is opened to the lateral hole, which axially extends through a center of the inner needle and whose another end is opened to a lower end of the inner needle axially below the circular seat contact, and, further, wherein the one end of the first injection bore is arranged axially above a position where the circular seat contact comes in contact with the conical inner circumferential wall and axially below a position where the another circular seat contact comes in contact with the conical inner circumferential wall, the one end of the second injection bore is arranged at the conical inner circumferential wall axially above the position where the another circular seat contact comes in contact with the conical inner circumferential wall, and, when the needle member shows the first lift, the fuel passage communicates only with the first injection bore through the clearance between the circular seat contact and the conical inner circumferential wall and, when the needle member shows the second lift, the fuel passage communicates with the second injection bore through a clearance between the another circular seat contact and the conical inner circumferential wall.
- 10. A fuel injection nozzle according to claim 8, wherein the inner and outer needles are provided with lift force transmitting means through which a lift force is transmitted from the inner needle to the outer needle at least when the needle member shows the second lift.
- 11. A fuel injection nozzle according to claim 8, wherein at least one of the outer circumference of the outer needle and the cylindrical inner circumferential wall is provided axially above the second injection bore with a ring shaped collection groove, the nozzle body member is provided with a collection passage whose one end communicates with the collection groove and whose another end communicates with a low pressure source, the outer needle is provided with a radial through-hole whose one end communicates with the ring shaped collection groove when the needle member does not lift and the inner needle is provided on outer circumference thereof with a ring groove coming in communication with another end of the radial through hole when the needle member shows the first lift, whereby the high pressure fuel entering a clearance between the outer circumference of the outer needle and the cylindrical inner circumferential wall is returned through the collection groove and the collection passage to the low pressure source and the high pressure fuel entering a clearance between an outer circumference of the inner needle and an inner circumference of the outer needle is returned through the ring groove, the radial through-hole, the collection groove and the collection passage to the low pressure source.
- 12. A fuel injection nozzle according to claim 1, wherein at least one of the outer circumference of the guide shaft and the cylindrical inner circumferential wall is provided axially above the second injection bore with a ring shaped collection groove and the nozzle body member is provided with a collection passage whose one end communicates with the collection groove and whose another end communicates with a low pressure source, whereby the high pressure fuel entering a clearance between the outer circumference of the guide shaft and the cylindrical inner circumferential wall is returned through the collection groove and the collection passage to the low pressure source.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2001-351182 |
Nov 2001 |
JP |
|
2002-149318 |
May 2002 |
JP |
|
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A |
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A |
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DeVriese et al. |
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A |
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Date |
Country |
63-51154 |
Apr 1988 |
JP |
5-321789 |
Dec 1993 |
JP |