JPH085341Y2 - Fuel injection nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a fuel injection nozzle for a diesel engine.

[Prior Art] There is a type of fuel injection nozzle disclosed in Japanese Utility Model Laid-Open No. 57-8362. This fuel injection nozzle is shown in FIG.
It has a structure as shown in FIG.

That is, the needle valve 3 is slidably inserted in the sliding hole 2 of the nozzle body 1 in the axial direction thereof. The tip portion of the needle valve 3 is a head portion 4 having a slightly larger diameter, and the head portion 4 projects outward from the sliding hole 2. The tip edge of the sliding hole 2 is connected to a taper hole 5 that gradually expands in diameter as it approaches the tip of the nozzle body 1, and the outer peripheral edge of the head portion 4 of the needle valve 3 abuts on the taper hole 5. The portion is the seat portion 6. The proximal end side of the needle valve 3 is inserted into the storage hole 8 of the nozzle holder 7. The needle valve 3 penetrates a sleeve 9 arranged in the storage hole 8, and a spring receiving member 10 is externally fitted and fixed to the base end of the needle valve 3. The spring receiving member 10 has an intermediate member 11 and a pressure receiving member 12. They are fixed and they move with the needle valve 3. The needle valve 3 is biased in a direction approaching the nozzle holder 7 (upward in the figure) by a nozzle spring 13 interposed between the sleeve 9 and the spring receiving member 10,
Normally, the valve closed state is maintained. A fuel passage 14 is formed in the needle valve 3 along the central axis from the base end face toward the tip end side, and the tip end reaches the vicinity of the head portion 4. A plurality of injection holes 15 are formed at the tip of the needle valve 3. One end of the injection hole 15 is opened to the sliding surface with respect to the nozzle body 1, and the other end is connected to the fuel passage 14. A fuel passage 16 is formed in the nozzle holder 7 so as to communicate with the storage hole 8. The fuel passages 14 and 16 are connected to each other through holes provided in the intermediate member 11 and the pressure receiving member 12.

In the fuel injection nozzle, the fuel pumped from the fuel injection pump is supplied to the fuel passage 16 of the nozzle holder 7. Then, the pressure of the fuel causes the needle valve 3 to move downward against the elastic force of the nozzle spring 13, and as a result, the head portion 4 of the needle valve 3 separates from the seat portion 6 of the nozzle body 1 and opens. When the valve is set, the injection hole 15 opens
17 is exposed to the outside from the sliding hole 2 and fuel is injected from there. In order to equalize the penetrating force of the fuel injected from each injection hole 15, the inside diameter of each injection hole 15 is made the same,
Further, the angle θ formed by the central axis of the needle valve 3 and the central axis of each injection hole 15 is made equal to make the length of the injection hole 15 equal.

[Problems to be solved by the invention] By the way, in the case of this fuel injection nozzle, fuel is injected into the injection hole.
Since it is injected from 15, the injection is directional. Therefore, when the needle valve 3 rotates, the fuel injection direction also rotates accordingly, which causes problems such as unstable engine performance. Therefore, it is necessary to provide a mechanism for making the needle valve 3 non-rotatable. . In the conventional fuel injection nozzle,
As shown in FIG. 11, a groove 18 along the axial direction is formed on the sliding surface of the needle valve 3 with respect to the nozzle body 1, and the nozzle body 1
The guide pin 19 fixed to the sliding hole 2 is inserted into the groove 18 and the groove 18 and the guide pin 19 are slidably engaged with each other. However, with this structure, there is room for improvement, such as the occurrence of astringency between the groove 18 and the guide pin 19 which may cause a malfunction.

Further, as is well known, in addition to the fuel injection nozzle, an intake valve, an exhaust valve, etc. are installed in the cylinder head, so the fuel injection nozzle is located directly above the center of the combustion chamber due to the arrangement of other devices such as the intake valve. In some cases, it cannot be attached toward the center of the combustion chamber, and there is no choice but to attach it obliquely into the combustion chamber. However, when the conventional fuel injection nozzle is mounted in such a posture, the inclination of the center axis of each injection hole 15 with respect to the center axis of the needle valve 3 is the same, so the direction of fuel injection into the combustion chamber is biased. There was a problem that fuel could not be injected into the entire combustion chamber. In order to eliminate this inconvenience, each injection hole 15 with respect to the central axis of the needle valve 3 depending on the mounting angle of the fuel injection nozzle.
There is also a method of individually changing the inclination of the central axis of the fuel injection method. However, although this method solves the problem of the injection direction, since the length of each injection hole 15 is different, the fuel penetration force is different for each injection hole. However, there was a problem that the fuel injection from each injection hole 15 varied.

The present invention has been made in view of the above-mentioned problems of the conventional technology, and an object thereof is to have a fuel injection direction invariant mechanism that is simple in structure and has no malfunction, and is attached to a combustion chamber. There is a need to provide a fuel injection nozzle that can perform good fuel injection into the combustion chamber even when the fuel injection nozzle is inclined.

[Means for Solving the Problems] The present invention has been made in order to achieve the above object, and its gist is to provide a nozzle body with a needle valve slidably inserted in a sliding hole of a nozzle body in an axial direction thereof. A seat portion located radially outside the sliding hole is formed at the tip of the body, and the head portion of the needle valve protruding from the sliding hole is seated on the seat portion to close the valve. In the fuel injection nozzle in which the needle valve moves toward the tip end side in the axial direction and the head part is separated from the seat part, the valve is opened.
The needle valve includes a first valve formed inside along the axial direction.
A fuel passage and a second fuel passage having one end opened to a sliding surface with respect to the nozzle body and the other end connected to the first fuel passage are provided, and a tip end portion of the nozzle body is provided with an inner peripheral surface of the sliding hole. A pressure equalizing chamber that is formed by an annular groove, and a plurality of identical ones that open at one end on the side wall of this pressure equalizing chamber and that at the other end are surfaces that face the needle valve head portion and that are radially inner than the seat portion. An inner diameter injection hole is provided, and a vertical sectional shape of a side wall of the pressure equalizing chamber is formed so as to form an arc having the same radius with the other end opening of each injection hole as a center. Located in the fuel injection nozzle.

[Operation] In the fuel injection nozzle of the present invention, the injection hole is provided in the nozzle body that is a fixed system, and one end of the injection hole is connected to the annular pressure equalizing chamber formed on the inner peripheral surface of the sliding hole. Since the fuel is supplied to the pressure equalizing chamber from the second fuel passage of the needle valve, the fuel injection direction can be kept constant even if the needle valve rotates.

Further, the side wall of the pressure equalizing chamber is formed so that the vertical cross-sectional shape thereof forms an arc having the same radius centered on the outlet side opening of each injection hole, so that the individual injection holes of each needle hole with respect to the central axis of the needle valve are formed. Even if the inclination of the central axis is different, the length of each injection hole can be made the same size, and the inner diameter of each injection hole is made the same size, so that the fuel penetration force is different for each injection hole. It is almost the same without any difference. Therefore,
Even when the fuel injection nozzle is mounted in an inclined posture with respect to the combustion chamber, the fuel can be injected so that good combustion conditions can be obtained.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings from FIG. 1 to FIG.

1 to 4 show an embodiment of a fuel injection nozzle 30 according to the present invention. FIG. 1 is an overall longitudinal sectional view of the fuel injection nozzle 30, and FIG. 2 is the same tip in a valve closed state. FIG. 3 and FIG. 4 are enlarged cross-sectional views of the portion in the valve-opened state.

The fuel injection nozzle 30 includes a nozzle body 31, a needle valve 32, and a nozzle holder 33. The nozzle body 31 is connected and fixed to the nozzle holder 33 by a nozzle nut 34, and a knock pin mounted between the nozzle body 32 and the nozzle holder 32.
It has been disabled by 35. The tip of the nozzle body 31 is frustoconical, and its tip surface 36 is the outer peripheral surface of the tip.
The taper surface has a larger inclination angle with respect to the axis than 31a. The nozzle body 31 has a sliding hole 37 that extends along the central axis from the base end surface toward the tip and opens to the tip surface 36. The needle valve 32 is inserted through the sliding hole 37 so as to be slidable in the axial direction thereof, and the outer peripheral edge of the tip surface 36 forms a seat portion 36a for the needle valve 32.

A pressure equalizing chamber 38 formed of an annular groove is formed on the inner peripheral surface of the sliding hole 37 located near the tip of the nozzle body 31 over the entire circumference thereof. Further, four nozzle holes 39 having the same inner diameter are formed at the tip of the nozzle body 31 at equal intervals in the circumferential direction. Each of the injection holes 39 has one end opened on the side wall 38a of the pressure equalizing chamber 38 and the other end opened on the tip surface 36 of the nozzle body 31 at a position extremely close to the seat portion 36a. As shown in FIG. 4, the centers of the other end openings 39a of the injection holes 39 are all located on one plane orthogonal to the axis of the nozzle body 31. on the other hand,
The central axis of each injection hole 39 has a different inclination with respect to the central axis of the nozzle body 31, and the inclination angle of each injection hole 39 is set so that the fuel is evenly injected into the combustion chamber. The optimum angle is individually set according to the mounting angle with respect to. The side wall 38a of the pressure equalizing chamber 38 is formed in a vertical cross-sectional shape so as to form an arc having the same radius R centering on the other end opening 39a of each injection hole 39. Therefore, all the injection holes 39 have the same length.

The needle valve 32 is composed of a rod portion 40 and an anchor-shaped head portion 41 formed at the tip of the rod portion 40, and the head portion 41 is projected outward from the sliding hole 37. The root portion 42 of the head portion 41 has a tapered surface that expands in diameter while returning to the base end side, and the outer peripheral edge of this root portion 42 is seated on the seat portion 36a of the nozzle body 31 when the valve is closed. ing. At this time, a space having a wedge-shaped cross section is formed between the base 42 and the tip surface 36 of the nozzle body 31, and the tip outer peripheral surface 31a of the nozzle body 31 and the head portion 4 are formed.
The outer peripheral taper surface 43 of 1 is flush with.
The proximal end side of the rod portion 40 of the needle valve 32 penetrates the sliding hole 37 and is inserted into the housing hole 44 of the nozzle holder 33. The needle valve 32 is formed with a first fuel passage 45 extending along the central axis from the base end surface of the rod portion 40 toward the tip thereof.
Has reached the head portion 41. A second fuel passage 46 is formed at a portion of the rod portion 40 located near the head portion 41. The second fuel passage 46 has an annular groove 47 formed on the outer peripheral surface of the rod portion 40 over the entire circumference, and the annular groove 47.
And a plurality of communication holes 48 that connect the first fuel passage 45 to each other. In the valve closed state shown in FIG. 2, the annular groove 47 and the pressure equalizing chamber 38 of the nozzle body 31 have a predetermined dimension in the axial direction of the needle valve 31 (hereinafter, referred to as throttle length) L.
It is designed to be located only apart. In addition, communication hole 48
Can be one.

On the other hand, the needle valve 32 inserted in the storage hole 44 of the nozzle holder 33
The rod portion 40 penetrates the maximum lift set shim 49 and the sleeve 50 housed in the housing hole 44. Further, a stopper 51 is non-removably fitted on the base end of the rod portion 40. The needle valve 32 is biased in a direction approaching the nozzle holder 33 (upward in the drawing) by a nozzle spring 52 interposed between the sleeve 50 and the stopper 51, and normally maintains the valve closed state. It is like this. still,
The valve opening pressure of the needle valve 32 depends on the stopper 51 and the nozzle spring 52.
It is set as desired by interposing a valve opening pressure adjusting shim 53 between the two. Further, the maximum lift of the needle valve 32 is restricted by the stopper 51 hitting the upper end of the sleeve 50.

The nozzle holder 33 is formed with a fuel passage 54 extending from the base end surface thereof toward the tip thereof, and the tip of the fuel passage 54 is connected to the storage hole 44. The outer peripheral surface of the base end portion of the nozzle holder 33 is formed as a male screw portion 55, and a fuel supply pipe whose one end is connected to a fuel injection pump (neither is shown)
The other end of is connected.

Next, the operation of the fuel injection nozzle 30 will be described.

When fuel is pumped from the fuel injection pump to the fuel injection nozzle 30 which is in the closed state, the fuel pressure in the fuel passage 54 and the storage hole 44 of the nozzle holder 33 and the fuel passages 45 and 46 of the needle valve 32 is increased. Rises, whereby the needle valve 32 begins to fall against the elastic force of the nozzle spring 52. As a result, the needle valve 32
The head portion 41 is separated from the seat portion 36a of the nozzle body 31, and the valve is opened.

Until the needle valve 32 is lowered from the closed state by the throttle length L, that is, as shown in FIG. 3, the lower end of the annular groove 47 of the second fuel passage 46 reaches the upper end of the pressure equalizing chamber 38 of the nozzle body 31. Until then, since the annular groove 47 is closed by the inner peripheral surface of the sliding hole 37, the fuel is not directly injected from the second fuel passage 46 into the pressure equalizing chamber 38. However, as long as the rod portion 40 of the needle valve 32 is slidable in the sliding hole 37, the rod portion 40
The outer peripheral surface and the inner peripheral surface of the sliding hole 37 are not completely in close contact with each other, and there is a very slight gap between them. Therefore, while the needle valve 32 is lowered by the throttle length L from the closed state, a small amount of high-pressure fuel is injected from the second fuel passage 46 through the above-mentioned gap into the pressure equalizing chamber 38, and further each injection hole 39. Is injected into the combustion chamber through. This is the first
It is the secondary fuel injection [I], and the primary fuel injection [I] has the characteristics that the penetration force is low, the injection rate is low, and the injection shape spreads like a film into a bowl shape as shown in FIG. Have

When the needle valve 32 further descends from the state shown in FIG. 3,
As shown in FIG. 4, the annular groove 47 gradually protrudes into the pressure equalizing chamber 38, the fuel flows out directly from the second fuel passage 46 into the pressure equalizing chamber 38, and further from each injection hole 39, the combustion chamber. Will be injected into. This is the second fuel injection [II], and the seventh
9 to 9 show the growth process of the secondary fuel injection [II]. The secondary fuel injection [II] is characterized by a larger penetration force and a higher injection rate than the primary fuel injection [I], and the injection shape is wide as in the primary fuel injection [I]. Instead, it has a strong convergence.

FIG. 5 shows a comparison between the primary fuel injection [I] and the secondary fuel injection [II] in which the horizontal axis represents the cam angle and the vertical axis represents the penetrating force. It is a cam angle corresponding to the length L. The state of fuel injection shown in FIGS. 6 to 9 is shown by points A and B in FIG. 5, respectively.
It corresponds to point, C point, and D point. It should be noted that the primary fuel injection [I] does not disappear even after the secondary fuel injection [II] is started in FIGS. 7 to 9 because the actual fuel injection cycle is temporally different. It is very short and the next primary fuel injection [I] is started before the previous primary fuel injection [I] disappears, so that the primary fuel injection [I] is continuous. Because it can be seen.

As described above, in this fuel injection nozzle 30, the primary fuel injection [I] having a low injection rate is performed in the initial stage of the fuel injection, and the secondary fuel injection [I] having a high injection rate in the latter half of the injection is performed.
I] will be performed, ideally, fuel injection will be performed, diesel knock will be very unlikely to occur, engine quietness will be improved, and in the exhaust gas after combustion.
Toxic substances hardly occurs, such as NO _X, it is possible to clean the exhaust gas.

The injection rate of the primary fuel injection [I] can be appropriately adjusted by changing the setting of the throttle length L.

Further, according to this fuel injection nozzle 30, the injection hole 39 is formed in the nozzle body 31 which is a fixed system, and one end of the injection hole 39 is provided on the inner peripheral surface of the sliding hole 37 of the nozzle body 31. Since it is connected to the annular pressure equalizing chamber 38, even if the needle valve 32 rotates, the fuel injection direction does not rotate and can be kept constant. The fuel-injection-direction invariant mechanism having such a structure is superior in structure to the conventional one, and is excellent in that malfunctions are less likely to occur.

Further, in this fuel injection nozzle 30, the inclination of the central axis of the injection hole 39 with respect to the central axis of the nozzle body 31 is set in advance to the optimum angle for each injection hole 39 according to the attachment angle with respect to the combustion chamber. The fuel injection from each injection hole 39 into the combustion chamber is prevented from being biased in one direction. Moreover, as described above, since the inner diameters of the injection holes 39 are the same and the lengths thereof are also the same size, the fuel penetrating force does not vary from one injection hole 39 to another, and they can be made almost the same. . Therefore,
The fuel can be evenly injected into the combustion chamber, and the fuel can be combusted well.

FIG. 10 is a sectional view of the tip end portions of the nozzle body 31 and the needle valve 32 in another embodiment of the fuel injection nozzle 30. The difference between this fuel injection nozzle 30 and that of the above-described embodiment is that the tip end surface 36 of the nozzle body 31 has a V-shaped cross section, and the root portion 42 of the head portion 41 of the needle valve 32 has a substantially cross-sectional shape. It is in the shape of a letter, these tip surface 36 and base 42
A gap having a substantially V-shaped cross section is formed between them, and the other end opening 39a of each injection hole 39 is located at the bent portion of the tip surface 36 of the nozzle body 31. Other points are the first
Since this is the same as the fuel injection nozzle 30 of the embodiment, the same reference numerals are given to the same mode parts and the description thereof will be omitted. Also in this fuel injection nozzle 30, the same effect as that of the first embodiment can be obtained.

This invention is not limited to the above-mentioned embodiment, and various modes can be adopted. For example, in the above-described embodiment, the second fuel passage 46 of the needle valve 32 is composed of the annular groove 47 and the communication hole 48. However, the annular groove 47 is not always necessary, and the second fuel passage 46 is formed by the diameter of the needle valve. It may be configured only with a passage extending in the direction.

Further, in the embodiment, in the valve closed state, the second fuel passage 46 of the needle valve 32 and the pressure equalizing chamber 38 of the nozzle body 31 are connected to the throttle length L.
However, the throttle length may not be provided. That is, the throttle length L may be 0,
Alternatively, even when the valve is closed, the second fuel passage 46 and the pressure equalizing chamber
38 may be directly connected. However, in that case, the primary fuel injection described in the above embodiment does not occur, and only the secondary fuel injection in the above embodiment is performed as the fuel injection.

Further, the number of injection holes 39 is not limited to four, and the design can be changed appropriately.

[Effect of the Invention] As described above, the present invention has the following excellent effects.

In the fuel injection nozzle of the present invention, the injection hole is provided in the nozzle body that is a fixed system, and one end of the injection hole is connected to the annular pressure equalizing chamber formed on the inner peripheral surface of the sliding hole. Since the fuel is supplied from the second fuel passage of the needle valve, there is an excellent effect that the fuel injection direction is constant and invariable even if the needle valve rotates. This fuel injection direction invariant mechanism is not only simpler in structure than the conventional one but also highly reliable in operation and extremely excellent.

Also, by forming the vertical cross-sectional shape of the side wall of the pressure equalizing chamber so as to form an arc of the same radius centered on the outlet side opening of each injection hole, the center of each injection hole with respect to the central axis of the needle valve Even if the axis inclination is different, the length of each injection hole can be made the same size, and moreover, by making the inner diameter of each injection hole the same, the fuel penetration force is different for each injection hole. And the penetrating force of the fuel injected from each injection hole can be made equal. Therefore, even when the fuel injection nozzle is attached in an inclined posture with respect to the combustion chamber, there is an excellent effect that the fuel can be injected so as to obtain good combustion conditions.

[Brief description of drawings]

The drawings from FIG. 1 to FIG. 10 show an embodiment of the present invention. FIG. 1 is a vertical sectional view of a fuel injection nozzle in the first embodiment, and FIG. Enlarged cross-sectional views of the nozzle body and the tip of the needle valve shown in FIG. 3, FIG.
Each drawing is an enlarged cross-sectional view corresponding to FIG. 2 showing a valve open state of the nozzle. FIG. 5 is a graph in which the horizontal axis represents the cam angle and the vertical axis represents the penetrating force of the injected fuel. FIGS. 6 to 9 show the fuel injection at the time points corresponding to points A to D in FIG. It is a figure which shows a mode. Further, FIG. 10 is an enlarged sectional view corresponding to FIG. 2 in another embodiment. Also, the eleventh
FIG. 12 is a vertical sectional view of a conventional fuel injection nozzle, and FIG. 12 is an enlarged sectional view of a tip portion of the nozzle. 30 ... Fuel injection nozzle, 31 ... Nozzle body, 32 ... Needle valve, 36
a ... Seat part, 37 ... Sliding hole, 38 ... Pressure equalizing chamber, 38a ... Side wall, 39
... injection hole, 39a ... other end opening, 41 ... head part, 45 ... first fuel passage, 46 ... second fuel passage.

Claims (1)

[Scope of utility model registration request] 1. A needle valve is slidably inserted in a sliding hole of a nozzle body in an axial direction of the nozzle body, and a seat portion located radially outward of the sliding hole is formed at a tip end portion of the nozzle body. When the head portion of the needle valve protruding from the sliding hole is seated on the seat portion, the valve is closed, and the needle valve moves axially toward the distal end side and the head portion is separated from the seat portion to open. In the fuel injection nozzle that is in a valve state, the needle valve includes a first valve formed inside along the axial direction.
A fuel passage and a second fuel passage having one end opened to a sliding surface with respect to the nozzle body and the other end connected to the first fuel passage are provided, and a tip end portion of the nozzle body is provided with an inner peripheral surface of the sliding hole. A pressure equalizing chamber formed of an annular groove is formed, and a plurality of identical ones having one end opened to a side wall of the pressure equalizing chamber and the other end being a surface facing the needle valve head portion and being radially inner than the seat portion. An inner diameter injection hole is provided, and a vertical cross-sectional shape of a side wall of the pressure equalizing chamber is formed so as to form an arc having the same radius centered on the other end opening of each injection hole. Fuel injection nozzle.