The present invention relates to a fuel injection valve to supply a fuel to an internal combustion engine and a motor vehicle internal combustion engine equipped with the fuel injection valve.
Emission standards of motor vehicle-exhaust gas have been tightened through the year. In order to meet such a trend, in a technical field of fuel injection valve equipped in a motor vehicle internal combustion engine, required is fine atomization of fuel and reduction of adhesion of fuel to an inner wall surface of an intake pipe by injecting the fuel toward a target position (e.g., two directions toward intake valves of the internal combustion engine) to reduce noxious emission HC (carbon hydride).
In conventional fuel injection valves, the following techniques are disclosed as a fuel spray pattern control means for injecting a fuel to a target position.
One is a way, as shown in Document D1, of applying swirl forces to respective fuel sprays injected from multiple nozzle holes and making such swirl forces differ from each other on a group-by-group basis in the multiple nozzle holes divided into plural groups. According to this conventional technique, a fuel spray with a large swirl force becomes an injection with a wide spray cone angel capable of promoting fine atomization of the fuel, and a fuel spray with a small swirl force becomes an injection with a narrow spray cone angle capable of promoting a penetration for travel of fuel in a straight-line. According to the combination of these fuel sprays with different swirl forces, a fine-atomized fuel spray can be carried by a fuel spray with a large penetration, and thereby, the reduction of adhesion of the fine atomized fuel spray to the inner wall surface of the intake pipe can be achieved.
Another is a way, as shown in Document D2, of forming a fan-shaped fuel spray pattern by colliding the fuel sprays injected from multiple nozzle holes with each other. Further this way is provided with two needle valves capable of selecting multiple nozzle holes, and by changing selection of the multiple nozzle holes upon stratified charge combustion operation and upon homogeneous combustion operation, it makes possible to change a pattern of the fuel spray.
In the above-described techniques, the way disclosed in the Document D1 teaches of using a fuel spray with a large penetration as one of the combined fuel sprays. According to the way, the one of fuel sprays although can have the large penetration, it tends to be inferior in performance of fine atomization of the fuel to that of the other fuel sprays with a wide spray cone angle of injection. Further, it is difficult to change the spray pattern in correspondence with change of a stroke amount of a valve element such a needle and change of fuel pressure. Next, in the way disclosed in the Document 2, it since uses two needle valves, the structure of the fuel injection valve increases in complexity and thereby increases in the cost of manufacturing products.
The subject of the present invention is to provide a fuel injection valve with a simple structure and capable of control a fuel spray pattern in correspondence with fuel pressure and/or the stroke amount of the valve element and to provide a motor vehicle internal combustion engine equipped with the fuel injection valve.
To solve the above-mentioned tasks, the present invention is basically configured as follows.
(1) That is, in a fuel injection valve for an internal combustion engine having multiple nozzle holes for fuel injection wherein the nozzle holes are constituted by at least a pair of nozzle holes and configured such that, upon valve opening of the injection valve, liquid columns of fuel injected from the pair of nozzle holes collide with each other before break-up of the liquid columns,
the fuel injection valve further comprises a fuel flow control portion that controls a flow of the fuel flowing into at least one of the pair of nozzle holes so as to make swirl forces of the fuel liquid columns injected from the pair of nozzle holes differ from each other.
(2) Regarding the swirl forces of the fuel liquid columns, for example, the fuel flow control portion is configured to apply a swirl force to a fuel injected from one of the pair of nozzle holes while applying a smaller or little swirl force to a fuel injected from the other of the pair of nozzle holes in comparison with the one nozzle hole. In this manner, those swirl forces from the pair of nozzle holes are set to be different from each other.
Further for example, the fuel flow control portion is configured to make fuel flow velocity distributions in a circumferential direction at inlets of the pair of nozzle holes differ from each other thereby to make the swirl forces between the nozzle holes differ from each other.
(3) For example, the multiple nozzle holes are provided in a nozzle plate. That is, the fuel flow control portion is configured on a top surface of the nozzle plate to be an upstream side surface of the nozzle plate.
3-1) The top surface of the nozzle plate is provided with a step height for making a difference in height on the top surface, and at least one pair of nozzle holes is provided at a lower portion to be a lower surface in the difference in height, wherein one of the pair of nozzle holes at the lower portion is placed close to a wall of the step height such that the inlet of the one of the pair of nozzle holes is subjected to control of the fuel flow with the wall of the step height. In this case, the wall of the step height configures the fuel flow control portion.
3-2) Otherwise, in the top surface of the nozzle plate, the inlet of at least one of the pair of nozzle holes is provided with a countersunk-like hole portion larger than a diameter of the nozzle hole. The countersunk-like hole portion configures the fuel flow control portion by offsetting a center of the countersunk-like hole portion with respect to a center of the nozzle hole provided with the countersunk-like hole portion.
3-3) Otherwise, the top surface of the nozzle plate is provided with a local hollow portion, and the inlet of one of the pair of nozzle hole is placed in the local hollow portion. The local hollow portion has an asymmetric shape with respect to a line connecting between a center of the nozzle plate and the center of the one nozzle hole placed in the local hollow portion, and thereby a part of the inlet of the one nozzle hole is close to a part of an edge wall of the local hollow portion, thus, the edge wall of the local hollow portion configures the fuel flow control portion.
3-4) Otherwise, the top surface of the nozzle plate is provided with a projection, and the inlet of one of the pair of nozzle holes is placed close to the projection, thus, a side wall of the projection configures the fuel flow control portion.
3-5) Otherwise, an end of a movable valve element of the fuel injection valve is provided with a flat face portion and a step height formed at an edge (edges) of the flat face portion, and one of the pair of the nozzle holes is placed close to a wall of the step height of the movable valve element such that the wall of the step height configures the fuel flow control portion.
By employing the above structure, the fuel flow control portion changes distributions and magnitudes of fuel flow velocity components (axis-direction velocity component and swirl velocity component) of the fuel flowing into the pair of nozzle holes, and thereby a difference of swirl components (including a case where zero swirl component is produced in one of the pair of nozzle holes) for the fuel is produced between the pair of nozzle holes. Accordingly, the respective liquid columns of the fuel injected from the pair of nozzle holes can have different kinetic energy respectively. As a result, when the liquid columns of the fuel injected from the pair of nozzle holes collide with each other and thereby a liquid film of the fuel is formed, the liquid film does not have a symmetrical shape with respect to the pair of nozzle holes and thereby the liquid film is deflected to the side of the fuel liquid column with kinetic energy smaller than the other side. When the liquid film is deflected in this manner, the distribution of liquid droplets after break-up of liquid film of the fuel follows a deflecting direction of the liquid film, and thus a fuel spray pattern can be changed.
The swirl components of fuel in the pair of nozzle holes can be controlled by changing the pressure applied to the fuel or the amount of valve stroke. With this arrangement, it is possible to change the fuel spray pattern in correspondence with the fuel pressure or the valve stroke.
According to the present invention, it is possible to change the direction and the pattern of the fuel spray in correspondence with the fuel pressure or the valve stroke, without deterioration of atomization for fuel spray, with a simple structure.
[
[
[
[
[
[
[
[
[
[
[
[
[
[
[
[
[
[
[
[
[
[
[
[
Hereinbelow, examples of the present invention will be described based on embodiments.
First, an embodiment 1 of the present invention will be described using
In
A casing 2 of the injection valve has a slim-shaped and thin-walled cylindrical body by press-working or cutting and partially drawing. The material of the casing 2 is ferrite stainless material mixed with flexible material such as titanium having a magnetic property.
One end side (top end side in
The outside of the casing 2 is provided with an electromagnetic coil 14 and a yoke 16 of magnetic material surrounding the electromagnetic coil 14. A stationary-side core (hereinbelow, referred to as a “stationary core”) 15 is inserted and fixed around a member (drawn part) located at a midpoint position in an axial direction inside the casing 2. The stationary core 15 is positioned inside the electromagnetic coil 14.
In the casing 2, the valve element 3 incorporated so as to move linearly reciprocally at a predetermined stroke between the nozzle body 5 and the stationary core 15, wherein the valve element 3 is integrally formed with a movable core (hereinbelow, referred to as an “anchor”) 4. That is, an upper end of the anchor 4 and a lower end of the stationary core 15 are in opposition to each other, and in a status where a spherical portion (ball valve) at an end of the valve element 3 is seated on a valve seat 30, the upper end of anchor 4 is located so as to be opposite to the lower end of the stationary core 15 keeping a gap for the predetermined stroke.
The valve element 3 has a hollow rod shape except the ball valve at its end. The anchor 4 and the hollow rod are formed by injection-molding magnetic metal powder by the MIM (Metal Injection Molding) or the like. The inside of the hollow rod of the valve element 3, the stationary core 15 and the anchor 4 constitutes a fuel passage.
As shown in
The nozzle body 5 is fixed to the inside of the casing 2 by appropriate fixing means such as welding.
The inside of the nozzle body 5 is provided with an inner circumferential surface for guiding an axial direction movement of the ball vale of the valve element 3 and a conical surface (tapered surface) including the valve seat 30 on which the ball valve of the valve element 3 is seated upon valve closing. A lower end of the tapered surface is provided with an outlet-side fuel through hole 11. The taper angle of the above-described tapered surface is about 90° (80° to 100°). This taper angle is an optimum angle (in which a grinding machine can be used to form the tapered surface in the best condition) to grind around the seat 30 and increase the roundness for the boll valve. Such a taper angel can maintain an exceedingly high seat characteristic for the valve element 3. Note that hardness of the nozzle body 5 with a tapered surface including the seat 30 is increased by quenching, and further, superfluous magnetism is removed by demagnetize processing. This valve element structure enables injection amount control without fuel leakage. Further, it is possible to provide a valve element structure having high cost performance.
A spring 12 as an elastic member is incorporated over the inside of the stationary core 15 to the inside of the anchor 4. The spring 12 applies a force to press the end of the valve element 3 against the nozzle body 5. The stationary core 15 is provided with a spring adjuster 13 to adjust the pressing force of the spring 12 to the valve element 3. Further, the fuel supply port 2a is provided with a filter 20 to remove foreign materials included in the fuel. Further, an O ring 21 is attached to the outer periphery of the fuel supply port 2a to seal supplied fuel.
A resin cover 22 is provided to cover the casing 2 and the yoke 16 by means of resin molding. The resin cover 22 has a connector 23 to supply electric power to the electromagnetic coil 14.
One end-side part of the fuel injection valve 1A is provided with a protector 24, which is a cylindrical member of e.g. resin material, and the one end of the protector 24 overhangs outward in a diameter direction from the casing 2. Further, an O-ring 25 is attached to one end-side part of an outer periphery of the casing 2. The O-ring 25 is arranged between the yoke 16 and the protector 24 to be prevented from dropping off, and for example, under a status where the one end-side part of the casing 2 is inserted into an injection valve-installation portion (not shown) provided on an intake pipe of the internal combustion engine, it seals a gap between the casing 2 and the injection valve-installation portion.
In the fuel injection valve 1, when the electromagnetic coil 14 as a valve drive actuator is in unenergized status, the end of the valve element 3 comes into contact with the seat 30 of the nozzle body 5 by the pressing force of the spring 12. In this status, the valve is in a valve-close status, and the fuel flowing from the fuel supply port 2a stays inside the casing 2.
When an electric current as an injection pulse is applied to the electromagnetic coil 14, a magnetic circuit is formed in the yoke 16, the core 15 and the anchor 4 which are made of magnetic material. The valve element 3 moves by the electromagnetic force of the electromagnetic coil 14 against the pressing force of the spring 12 until contacting with the lower end surface of the stationary core 15. In a status where the valve element 3 has moved to the stationary core 15-side, the valve is in the valve-open status, and a fuel passage is formed between the valve element 3 and the seat 30. The fuel in the casing 2 flows in the nozzle from the peripheral portion of the valve element 3, and then is injected from the fuel nozzle holes. The fuel injection amount is controlled by controlling timing of selection between the valve-open status and the valve-close status by moving the valve element 3 in the axial direction of the injection valve in correspondence with the injection pulse intermittently applied to the electromagnetic coil 14.
The nozzle plate 6 (shown in
As shown in an arrangement diagram of the conventional fuel nozzle holes in
The spray angle of the two directional sprays is defined as follows (one example). That is, θ1 is defined as an angle formed between centers of the two sprays 18a and 18b, which is observed from a direction vertical to a plane including the two directions of the two fuel sprays 18a and 18b. θ2 is defined as a divergence angle of the respective sprays 18a and 18b, which is also observed from the direction vertical to the plane including the two directions of the two fuel sprays 18a and 18b. θ3 is defined as a divergence angle of a spray 19, which is observed from the right angle direction with respect to the above-mentioned plane.
In the present embodiment, a step height 33a is provided on the top surface of the nozzle plate 6, accordingly, planes having a difference in height is formed in the top surface of the nozzle plate, in which a higher (upper step side) surface is referred to as a projection portion 35a, and a lower (lower step side) surface is referred to as a depression portion 34a.
As shown in
As described in
In
In the present embodiment shown in
Regarding the nozzle holes 9a and 9b on the projection portion 35a, even when the fuel pressure is changed, as the both flows mainly have the nozzle hole axis-directional velocity component and the same ratio, the collision energies of the fuel liquid columns injected from the both nozzle holes are the same together. The directionality of the fuel spray liquid film shaped after the collision does not deflect and keeps in the same status as indicated with a dotted-line arrow 28c.
The change amount (including the directionality) of the liquid film shape can be controlled by changing the distance between the step height 33a and each nozzle hole. As shown in
Further, in addition to the changing of fuel pressure, when the stroke of valve element is changed, the amount of fuel inflow into the nozzle hole is changed. As a result, it is possible to make a swirl velocity component as well as in the case of changing the fuel pressure. Regarding the valve element stroke, it is possible to perform stepless variable stroke control using a piezo device in place of the electromagnetic coil as a driving source. In use of the electromagnetic coil (solenoid), it is possible to perform two-stage variable stroke control with two driving circuits.
Further, regarding the step height 33a, the height H is equal to or higher than ( 1/10)R with respect to a radius of each nozzle hole. Further, for the step height 33a to exert an influence upon the swirl forces at the nozzle holes 7a and 7d, it is necessary to set a distance between the step height and the nozzle holes (i.e. the shortest distance between the step height and the pair of nozzle holes) to 3R or shorter. Because the velocity distribution of the fuel flowing into each nozzle hole depends on an area (A) of the fuel through hole on the upstream of inlets of the nozzle holes in contact with the inlets of the nozzle holes, i.e., the velocity distribution is proportional to 2nd power of the radius R of the nozzle hole. As a velocity of the flow flowing into each nozzle hole is inversely proportional to the above-described the area (A) of the fuel through hole, the step height does not influence the fuel flow velocity distribution at the inlet of the nozzle hole on the condition that the above-described area (A) of the through hole is equal to or greater than 10 times of an area (Ao) of the nozzle hole. Accordingly, on the condition that a radius of the through hole is equal to or greater than about 3.3 times of the radius of the nozzle hole, the step height does not influence the fuel flow velocity distribution at the inlet of the nozzle hole. According to this calculation, to form a swirl velocity component with the step height, it is necessary to set the above-described shortest distance between the step height and the pair of nozzle holes to 3R or shorter. Further, on the condition that the step height is in the same order of the nozzle hole size, the step height is effective only for formation of swirl velocity in the nozzle hole. When the step height is ( 1/10) R of the radius of the nozzle hole, the distribution ratio is 1-order smaller, and invalid in the swirl velocity formation. Accordingly, the lower limit of the step height is ( 1/10)R.
Note that in the nozzle plate 6 of the present embodiment, the depression portion 34a, which is a region facing a lower end of the tapered surface of the nozzle body 5, i.e., a region facing the fuel through hole 11, is formed by a flat surface continuously together with a region of the outside of the depression portion as shown in
In the nozzle plate 6, regarding the forms of the step height provided on the top surface of the region facing the fuel through hole 11 and the depression portion formed with the step height, they are not limited to those in the embodiment 1, but various forms may be proposed as follows.
In the present embodiment, as shown in
In the present embodiment, a swirl force in the same direction as that in the embodiment in
Next, description will be done as to the form of the nozzle plate 6 in an embodiment 3 using
In the present embodiment, as shown in
In the present embodiment, a swirl force is formed at the nozzle hole 7a in a direction opposite to that of the embodiment 1 in
Next, description will be done as to the form of the nozzle plate 6 of an embodiment 4 using
In
All the nozzle holes are provided in the depression portion 34d side.
In the present embodiment as well as the embodiment 3, a swirl force is formed at the nozzle hole 7a in a direction opposite to that of the embodiment 1. In the present embodiment as well as the embodiment 3, in the nozzle hole 7a, as a part near the step height 33d is in a position where fuel flowing into the nozzle hole 7a is regulated (the flow velocity is reduced), when the fuel pressure is in a low state and thereby the swirl velocity component is reduced, the nozzle hole axis-directional velocity component is increased, and the kinetic energy of the fuel flowing into the nozzle hole 7b is larger than that of the fuel flowing into the nozzle hole 7a.
As a result, the fuel liquid film is deflected to a dotted-line arrow in the figure. Contrarily, when the fuel pressure increases, a difference of swirl forces is increased between the pair of nozzle holes 7a and 7b (the swirl force at the nozzle hole 7b becomes larger), and the liquid film is deflected from the dotted-line arrow toward a solid-line arrow in the figure. In the present embodiment, as the step height 33d has a curved surface, the swirl component can be easily formed, and a stronger swirl force can be formed in comparison with that of the embodiment in
Next, description will be done as to the form of the nozzle plate 6 in an embodiment 5 using
In the present embodiment, a step height 33e is formed with two parallel lines (illustration of the other step height with the parallel lines is omitted) so as to have a direction different from that of
In the present embodiment as well as the above-described embodiments, a difference of swirl forces is produced between the pair of nozzle holes 7a and 7b (also between the not shown nozzle holes 7c and 7d) by increase of the fuel pressure, and the liquid film is deflected from a dotted-line arrow to a solid-line arrow in the figure.
Next, description will be done as to the form of the nozzle plate 6 in an embodiment 6 using
In the present embodiment, a step height 33f is formed in a central region so as to have a direction different from that of
In the present embodiment, which is different from the above-described embodiments, the step height 33f is formed in the vicinity of the nozzle hole 7b and the not shown nozzle hole 7c. Further, a shape of the step height 33f has an S-shaped curve around the nozzle hole 7b (7c) along a part of the nozzle hole 7b (7c).
In the present embodiment, a difference of swirl forces is produced between the pair of nozzle holes 7a and 7b (and 7c and 7d), and the liquid film is deflected from a dotted-line arrow to a solid-line arrow in the figure by increase of the fuel pressure.
Next, description will be done as to the form of the nozzle plate 6 of an embodiment 7 using
In the present embodiment, instead of the step height provided on the nozzle plate in the above-described embodiments, in the pair of nozzle holes 7a and 7b (and in the not shown nozzle holes 7c and 7d), a countersunk-like hole portion 36a is provided at an inlet of the one nozzle hole 7a (7d).
The countersunk-like hole portion 36a is provided at a position where a countersunk center is offset with respect to a line connecting between a center (o) of the nozzle plate and a center of the inlet of the nozzle hole 7a (7d). Accordingly, when the fuel flowing in a centripetal direction of the nozzle plate on the top surface of the nozzle plate upper flows into the countersunk-like hole portion, a swirl velocity component as indicated with an arrow is produced at the inlet of the nozzle hole 7a. With this effect, the fuel liquid film formed with the pair of nozzle holes 7a and 7b (and the not shown nozzle holes 7c and 7d) is deflected from a dotted-line arrow to a solid-line arrow in the figure by increase of the fuel pressure. The countersunk-like hole portion 36a provided in the present embodiment may be a conical shape or a cylindrical shape with a flat bottom. Further, the shape of the countersunk-like hole portion is not necessary to be a circle shape but may be a oval or approximate circle shape. In the present invention, it is possible to form the countersunk-like hole portion and the nozzle holes by punching through the nozzle plate using the same pin and therefore perform low-cost manufacturing. A radius of the countersunk-like hole portion is equal to or smaller than 3R with respect to a radius R of the nozzle hole. A depth of the countersunk-like hole portion must be equal to or larger than ( 1/10)R. The velocity distribution of the fuel flowing into the nozzle hole depends on an area of the fuel through hole provided on the upstream side of the inlet of the nozzle hole, i.e., the velocity distribution is proportional to the 2nd power of the nozzle hole radius R. As the fuel inflow velocity into the nozzle hole is inversely proportional to the above-described the area (A) of the fuel through hole, the countersunk-like hole portion does not influence the fuel flow velocity distribution at the inlet of the nozzle hole on the condition that the above-described the area of the fuel thorough hole is equal to or greater than 10 times of an area of the nozzle hole. Accordingly, on the condition that a radius of the countersunk-like hole portion is about 3.3 times of the nozzle hole diameter, the countersunk-like hole portion does not influence the fuel flow velocity distribution at the inlet of the nozzle hole. According to this calculation, to produce a swirl velocity component with the countersunk-like hole portion, it is necessary to set the radius of the countersunk-like hole portion to equal to or shorter than 3R with respect to the nozzle hole radius R. Further, the depth of the countersunk-like hole portion contributes to the direction of fuel flowing into the nozzle hole. When the depth is equal to or less than 1/10 of the nozzle hole radius, the contribution to the inflow velocity change can be ignored. From this calculation, the above-described depth of the countersunk-like hole portion must be equal to or greater than 1/10 of the nozzle hole radius. Further, the upper limit of the depth is limited with the plate thickness of the nozzle plate and processing cost.
Next, description will be described as to the form of the nozzle plate 6 in an embodiment 7 using
In the present embodiment, countersunk-like hole portions 36b, 36c and 36d are provided at the inlets of all the nozzle holes. Each countersunk-like hole portion is provided such that a center of the countersunk-like hole portion is in a position offset with respect to a line connecting between the center (O) of the nozzle plate and a center of each nozzle hole. Accordingly, when the fuel flowing in a centripetal direction of the nozzle plate on the top surface of the nozzle plate flows into the countersunk-like hole portion, a swirl velocity components indicated with arrows is produced at the inlets of the nozzle hole 7a, 7b and 9a. In
Next, description will be done as to the form of the nozzle plate 6 in an embodiment 9 using
In the present embodiment, regarding the pair of nozzle holes 7a and 7b (also in the not shown nozzle holes 7c and 7d), a depression portion 34g is provided at the periphery of one nozzle hole 7a (7d), and a step height 33g is formed by a edge of the depression portion 34g. Thus, a projection portion 35g and the depression portion 34g are formed in the top surface of the nozzle plate.
The nozzle hole 7a (7d) is provided in the depression portion 34g, and other nozzle holes are provided in the projection portion 35g. As shown in
Next, description will be done as to the form of the nozzle plate 6 in an embodiment 10 using
In the present embodiment, in the pair of nozzle holes 7a and 7b (also in the not shown nozzle holes 7c and 7d), a projection 37 is provided near either nozzle hole 7a or 7d. Accordingly, apart of the fuel flowing in a centripetal direction of the nozzle plate on the top surface of the nozzle plate is blocked with the projection 37. As a result, a swirl velocity component is produced in the fuel at the entrance of the nozzle hole 7a as indicated with arrows. With this arrangement, it is possible to deflect the liquid film shape from a dotted-line arrow to a solid-line arrow in the figure by increase of the fuel pressure. The height H of the projection must be equal to or greater than 1/10 of the radius R of the nozzle hole. The height of the projection plays a role of contributing the directional change of the fuel flowing into the nozzle hole, however, the contribution to the inflow velocity change can be ignored when the height is 1/10 or less than the nozzle hole radius. From this calculation, the height of the projection must be equal to or greater than 1/10 of the nozzle hole radius. Further, the upper limit of the height depends on the processing cost and space size formed with the nozzle plate and the valve element.
Next, description will be done as to the form of the nozzle plate 6 and the form of the valve element 3 in an embodiment 11 using
In the present embodiment, the form of the nozzle plate 6 and the arrangement of the nozzle holes are the same as those of the conventional art shown in
According to the present embodiment, when the stroke amount of the valve element is small, as the step height 38 is closer to the inlet of the nozzle hole 7b (7c), a swirl velocity component as indicated with arrows is produced at the inlet of the nozzle hole 7b (7c). Accordingly, when the stroke amount of the valve element is small, it is possible to deflect the liquid film formed with a pair of nozzle holes from a dotted-line arrow to a solid-line arrow in the figure by increase of the fuel pressure.
According to the present embodiment, it is possible to change the liquid film shape including the directionality by changing the valve element stroke amount in correspondence with engine status.
Next, description will be done as to the nozzle plate 6 in an embodiment 12 using
In the present embodiment, as shown in
That is, as the step heights 41a and 41b are provided on the top surface of the nozzle plate, a projection portion 41c is formed in a central region, and the two depression portions 41d and 41e are formed on the both sides of the projection portion. On the depression portion 41d side, the nozzle holes 40a and 40b are arranged, while the nozzle holes 40c and 40d are arranged on the depression portion 41e side.
The fuel liquid columns injected from two nozzle holes of each pair collide with each other to form a liquid film. In this case, ones of the pairs of nozzle holes, the nozzle holes 40b and 40c near step heights 41a and 41b are influenced by these step heights. More particularly, in the nozzle hole 40b (40c), as a part near the step height 41a (41b) is in a position where the fuel flowing into the nozzle hole 40b (40c) is regulated (the flow velocity is reduced), when the fuel pressure is in a low state and thereby the swirl velocity component is reduced, the nozzle hole axis-directional velocity component is increased, and the kinetic energy of the fuel flowing into the nozzle hole 40a (40d) is larger than that of the fuel flowing into the nozzle hole 40b (40c). As a result, the fuel liquid film is deflected from a solid line to a dotted-line arrow in the figure. Then, when the fuel pressure increases, the difference of swirl force between the pair of nozzle hole 40b (40c) and nozzle hole 40a (40d) is increased (the force in the former nozzle hole is memorably increased. The latter is approximately the axis-directional velocity component). The liquid film is moved from the dotted-line arrow to the solid-line arrow in the figure.
According to the nozzle plate in the present embodiment, it forms one-directional fuel spray, the liquid column injected from an nozzle hole is injected in a vertically-downward direction with respect to the nozzle plate. Accordingly, the angle of collision upon formation of collision liquid film can be wider than the case of two-directional sprays. As a result, the collision force is increased and the liquid film is thinned, and better fine atomization of the fuel spray can be obtained in comparison with the two-directional sprays.
Next, description will be done as to the nozzle plate 6 in an embodiment 13 using
In the present embodiment as well as the embodiment 12, the arrangement of the fuel nozzle holes is to form a fuel spray injected in one direction wherein, when using the definition of the spray angles in
In the present embodiment, in place of the step heights 41a and 41b in the embodiment 12, countersunk-like hole portions 42a and 42b are provided in one nozzle holes 40b and 40c in the respective pairs of nozzle holes 40a and 40b (40c and 40d). The center of the countersunk-like hole portion is offset with respect to a line connecting between the center (O) of the nozzle plate and the center of the nozzle hole 40b (40c). This offset effect makes fuel flow regulation as in the case of the embodiment 12. Upon fuel inflow in the countersunk-like hole portion, a swirl velocity component is produced, and as a result, a difference of swirl forces is produced between each pair of nozzle holes. The shape of the collision liquid film is deflect from a dotted-line arrow to a solid-line arrow by increase of the fuel pressure.
An internal combustion engine 101 has an intake port 106 to which a fuel injection valve 1 is equipped, an intake pipe 105 as a passage to take in air from the outside, and an intake valve 107 to supply fuel spray and the air into a combustion chamber 102 of each cylinder. A fuel spray 90 from the fuel injection valve 1 is fed to the combustion chamber 104 via the intake valve 107 upon valve opening.
The air-fuel mixture fed into the combustion chamber 102 is compressed with a cylinder 103, and ignited via an ignition plug 104. Exhaust gas after combustion is discharged via an exhaust valve 108, and at the exhaust process, passed through a not shown exhaust emission purification catalyst.
As shown in
According to the above-described respective embodiments, it is possible to change the direction and form of fuel spray in correspondence with fuel pressure or valve stroke with a simple structure without deterioration of atomized droplet-diameter of the fuel spray. Accordingly, the spray pattern of the injected fuel can be changed.
Further, it is possible to realize a variable spray at a low cost with a simple structure different from the conventional invention (Patent Document 2: JPA 2003-328903) showing a complicated structure using two needle valves.
Further, in the conventional invention (Patent Document D1: JPA 2006-336577), a fuel spray having a penetration although is used to carry a fine-atomized fuel spray, the diameter of each droplet in the fuel spray trends to become large to keep the penetration. In the present embodiment, the change of spray pattern is realized by reflecting the above-described liquid film. Since the diameter of the fine droplet of the fuel spray greatly depends on the thickness of liquid film but does not much depend on the bend of liquid film, it is possible to change the spray pattern without deterioration of the diameter of the fine droplet of the fuel spray.
Further, in the present embodiment, particularly upon cold engine status, the spray is widened to enlarge the spray surface area to promote natural evaporation. Upon engine warming up, the spray is narrowed to be brought to collide with the intake valve, to cause evaporation with incoming heat from the intake valve. This enables improvement in exhaust performance and output performance.
Number | Date | Country | Kind |
---|---|---|---|
2010-164633 | Jul 2010 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/JP2011/066300 | 7/19/2011 | WO | 00 | 1/31/2012 |