JP2006316653A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device compatibly establishing suppression of valve open bounce based on squeeze effect and valve close response. <P>SOLUTION: The fuel injection device 1 is provided with a fixed core 3 fixed in a valve body 2 and an armature 5 reciprocatably stored in a tip side of the fixed core 3 and provided with a needle valve 4 in a tip side. A spring 7 is gripped between the fixed core 3 and the armature 5. A recess part 8 is provided in a base section of the armature 5 and a moving element 9 made of magnetic body is stored in the recess part 8. Only a base end side end surface 11 of the moving element 9 adheres on a fixed core side opposing surface 3a at a time of valve open. Consequently, valve open response is improved. On the other hand, valve close bounce is suppressed by squeeze effect between the tip side end surface 10 of the moving element 9 and an armature side second opposing surface 5b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electromagnetic fuel injection device used for an internal combustion engine, and more particularly to a fuel injection device capable of improving the opening / closing operation of a valve during fuel injection.

  2. Description of the Related Art Conventionally, a fuel injection device used for an internal combustion engine is provided with a fixed core having a coil inside a valve body in which an injection hole is formed, and an armature that reciprocates within the valve body when the coil is energized. There are things with different configurations. This armature has a configuration in which a needle valve for opening and closing the injection hole is provided on the distal end side. That is, the needle valve is reciprocated integrally with the armature according to the energized state of the coil to inject and stop the fuel from the injection hole. Further, in such a fuel injection device, a needle valve or a spring that presses an armature integrated with the needle valve is mounted to close the needle valve.

  In the fuel injection device having such a configuration, the armature attracted to the fixed core side when the coil is energized causes the armature (needle valve) to move to the fixed core when the valve is opened due to the squeeze effect generated by approaching the fixed core. Slight vibration (open valve bounce) of the needle valve generated by the collision is suppressed. However, while the squeeze effect is effective in suppressing the valve opening bounce, the valve closing delay and the valve closing response are deteriorated when the valve is closed (reverse squeeze phenomenon).

  Thus, since the squeeze effect affects the opening / closing operation of the needle valve, a proposal has been made to improve the operation characteristics of the needle valve in consideration of the squeeze effect (Patent Document 1). Patent Document 1 discloses the following fuel injection valve. In the fuel injection valve described in Patent Document 1, the needle valve movably accommodated in the body is disposed so as to be slightly inclined with respect to the axis of the body. Further, a stopper plate with which the stopper portion on the needle valve side abuts is provided on the body side, and an inclination angle with respect to a vertical plane orthogonal to the axis of the needle valve is provided between the stopper portion and the stopper plate.

JP 2000-329035 A

  In the fuel injection valve described in Patent Document 1, the angle of the needle valve with respect to the body is inclined, or an inclination angle with respect to a vertical plane orthogonal to the axis of the needle valve is provided between the stopper portion and the stopper plate. By doing so, an appropriate squeeze force is generated at the time of opening and closing of the valve, and good operating characteristics of the needle valve are realized.

  However, high dimensional accuracy and work accuracy are required to achieve a desired inclination angle at a predetermined location in the fuel injection valve. In addition, many processes are required to achieve adaptation for different fuel injection systems, which may increase costs.

  Therefore, the present invention does not require special processing or the like for realizing a desired inclination angle during processing, and can achieve both the suppression of valve opening bounce based on the squeeze effect and the valve closing response. It is an issue to provide.

  In order to achieve the above object, a fuel injection device according to the present invention includes a valve body in which an injection hole is formed, a fixed core mounted in the valve body, and a tip side of the fixed core in the valve body. An armature provided with a needle valve that opens and closes the injection hole on the distal end side thereof, a coil that causes the armature to approach and separate from the fixed core when energized, and the needle valve In the fuel injection device having an armature pressing means for pressing the armature so as to be in a valve-closed state, a front end side end surface of the fixed core is a fixed core side facing surface, and the armature has the fixed core side facing surface An armature-side first opposing surface that faces the armature, and an armature-side second opposing surface that is located on the tip side of the armature-side first opposing surface. A movable body made of a magnetic material that reciprocates independently from the armature between the second facing surface on the side of the arm and the facing surface on the side of the fixed core. A structure is formed in which a gap is formed between the fixed core side facing surface and the armature side first facing surface in a state where the proximal end side surface is in close contact with the fixed core side facing surface. (Claim 1). In the present specification, a side where an injection hole is provided in a normal fuel injection device is referred to as a distal end side, and the other end side is referred to as a proximal end side.

  The present invention is made by paying attention to the fact that the squeeze effect occurs between the distal end surface of the fixed core and the proximal end surface of the armature, and the magnitude of the squeeze effect is related to the contact area between the fixed core and the armature. It is a thing. Here, the suppression of valve opening bounce by the squeeze effect and the contradiction of the valve closing response are summarized as follows. Normally, when the contact area between the armature and the fixed core increases, the valve opening bounce suppression effect is enhanced by the squeeze effect. However, when the valve is closed, it is difficult to separate the armature from the fixed core, and the valve closing response is deteriorated. On the other hand, if the contact area between the armature and the fixed core is reduced, the valve closing response is improved, but it is disadvantageous in terms of suppressing the valve opening bounce.

  In view of such circumstances, the fuel injection device of the present invention includes a mover separate from the armature integrated with the needle valve, and only the base end side end face of the mover has a fixed core when the valve is opened. It is set as the structure closely_contact | adhered with the front end side end surface. For this reason, the fixed core side compared to the conventional one in which the front end side end surface of the fixed core, that is, the substantially entire surface of the base end side end surface of the armature facing the fixed core side facing surface is in close contact with the fixed core side facing surface The contact area with the opposing end surface can be reduced. As a result, the reverse squeeze effect can be reduced and the valve closing response of the needle valve integrated with the armature can be improved.

  Since the contact area of the fixed core side facing surface is thus reduced, the squeeze effect between the fixed core and the armature is reduced, and as a result, the valve opening exerted between the fixed core and the armature is reduced. The bounce suppression effect is also reduced. However, in the fuel injection device of the present invention, it is possible to obtain a squeeze effect between the armature-side second facing surface and the tip end surface of the moving element, thereby reducing the squeeze effect between the fixed core and the armature. Minutes can be compensated for and the effect of suppressing valve opening bounce can be obtained.

  In such a fuel injection device, for example, a recess may be provided on the base end side of the armature, and the bottom surface of the recess may be configured as the armature-side second opposing surface (Claim 2). That is, it can be set as the structure which accommodates a moving element in this recessed part. When the concave portion is formed in this way, a small diameter cylindrical portion and a shoulder portion continuous to the small diameter cylindrical portion are formed on the proximal end side of the moving element, and the shoulder portion is formed at the opening end portion of the concave portion. It can be set as the structure which formed the latching | locking part which latches (Claim 3). The moving element according to the present invention is made of a magnetic material, and is pulled toward the fixed core separately from the armature depending on the energization state of the coil. However, the moving element forms a shoulder portion and the shoulder portion is locked to the opening end of the recess. By forming the locking part, after the shoulder is locked to the locking part when the valve is opened, the moving element and the armature move toward the base end side, that is, the fixed core side by the magnetic force generated by the coil. Gravitate. In addition, by setting it as such a structure, a small diameter cylindrical part is guided by the latching | locking part, and a moving element can be reciprocated.

  Further, when the concave portion is provided on the base end side of the armature as described above, it is possible to adopt a configuration in which a passage for communicating the inside and outside of the concave portion is formed in the armature and / or the moving element. 4). In the fuel injection device of the present invention, a squeeze effect is obtained between the end surface on the front end side of the moving element and the second armature-side facing surface formed on the armature. When a recess is provided on the base end side of the armature and the bottom surface of the recess is the armature-side second facing surface, fuel must be present in the recess to obtain a sufficient squeeze effect. Become. Therefore, if a passage is formed in the armature and / or the moving element to communicate the inside and outside of the recess, the fuel supplied into the valve body can be drawn into the recess and a sufficient squeeze effect can be obtained. be able to.

  According to the present invention, there is provided a mover made of a magnetic material that reciprocates separately from the armature, and in the valve open state, only the proximal end surface of the mover having a small area is the distal end surface (fixed core side) of the fixed core. The valve closing response can be improved. Further, during the valve opening operation, the squeeze effect can be obtained between the armature-side second facing surface and the tip end surface of the moving element, so that the valve opening bounce can be suppressed. The fuel injection device having such a configuration can be manufactured without super-precision processing.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic view showing a main part of a fuel injection device 1 of the present invention. The fuel injection device 1 includes a valve body 2 in which an injection hole 2 a is formed at a tip portion, and a fixed core 3 that is fixedly mounted in the valve body 2. Further, an armature 5 having a base end portion made of a magnetic material and including a needle valve 4 which is accommodated in the valve body 2 so as to be reciprocally movable toward the distal end side relative to the fixed core 3 and which opens and closes the injection hole 2a. I have. The needle valve 4 is welded to the distal end side of the armature 5 and constitutes a part of the armature 5. The fuel injection device 1 further includes a coil 6 that moves the armature 5 toward and away from the fixed core 3 according to an energized state. The coil 6 is mounted in a form embedded in the fixed core 3 as shown in the figure. A spring 7 corresponding to the armature pressing means in the present invention is sandwiched between the coil 6 and the armature 5 thus mounted. The armature 5 is urged toward the distal end side of the valve body 2 by the spring 7 so that the needle valve 4 is closed. A recess 8 is provided at the base end portion of the armature 5, and a moving element 9 made of a magnetic material is accommodated in the recess 8.

  FIG. 2 is an enlarged cross-sectional view of a corresponding portion with respect to detailed dimensions, shapes, and the like around the fixed core 3 and the armature 5 of the fuel injection device 1 having the basic configuration as described above, and an enlarged cross-sectional view of the proximal end portion of the armature 3 and FIG. 4 which is an enlarged sectional view of the moving element 9 will be described. FIG. 2 shows a closed state in which the injection hole 2 a is closed by the needle valve 4.

  First, in the fixed core 3, the front end side end surface denoted by reference numeral 3a is the fixed core side facing surface in the present invention. Next, the armature 5 has the concave portion 8 formed in the base end portion as described above, and the surface to which the reference numeral 5a is attached faces the fixed core side facing surface 3a in the armature side first facing surface in the present invention. The bottom surface of the concave portion 8 denoted by reference numeral 5b is the armature side second facing surface in the present invention. For this reason, the armature-side second facing surface is located on the tip side of the armature-side first facing surface as shown in FIG. In addition, a locking portion 8 a is formed at the opening end of the recess 8 to lock a shoulder portion 9 b of a moving element 9 described later.

  A moving element 9 as shown in FIG. 4 is accommodated in the recess 8. The mover 9 has a small-diameter cylindrical portion 9a formed on the base end side, that is, the side positioned on the opening side of the concave portion 8 when accommodated in the concave portion 8, and further a shoulder continuous with the small-diameter cylindrical portion 9a. A portion 9b is formed. Similar to the base end portion of the armature 5, such a moving element 9 is made of a magnetic material and reciprocates separately from the armature 5 by a magnetic field generated by the energized state of the coil 6 embedded in the fixed core 3. Reference numeral 10 indicates a distal end side end face of the movable element 9, and reference numeral 11 indicates a proximal end end face of the movable element 9.

  Such a mover 9 is accommodated in the recess 8 as shown in FIG. The state shown in FIG. 2 is a closed state in which the injection hole 2a is closed by the needle valve 4 as described above, but the distal end side end surface 10 of the moving element 9 and the armature side second opposing surface 5b in the recess 8 A gap b is formed between the locking portion 8a and the shoulder portion 9b in a state where the contact portions are in close contact with each other. A gap c is formed between the armature-side first facing surface 5 a and the proximal-side end surface 11 of the moving element 9. The armature 5 and the mover 9 maintain the positional relationship shown in FIG. 2 even when the valve is opened, and only the base end side end surface 11 is in close contact with the fixed core side facing surface 3a. As in the state shown in (4) in FIG. 5, the gap c between the fixed core side facing surface 3a and the armature side first facing surface 5a at the time of opening the valve is maintained. In the state shown in FIG. 2, a gap a is formed between the base end side end surface 11 of the moving element 9 and the fixed core side facing surface 3 a of the fixed core 3. The gap a and the gap b between the locking portion 8a and the shoulder portion 9b have a relationship of a> b.

  Operations of the fixed core 3, armature 5, and mover 9 of the fuel injection device 1 configured as described above will be described with reference to FIGS. 5 and 6. FIG. 5 shows the order from the closed state shown in (1) to the opened state shown in (4). FIG. 6 shows the moving state of the mover 9 and the armature 5 from the reference position corresponding to the states (1) to (4) in FIG.

  First, the state (1) in FIG. 5 is a closed state in which the coil 6 is not energized and the needle valve 4 closes the injection hole 2a. In this state, the distal end side end surface 10 of the moving element 9 and the armature side second facing surface 5b are in close contact with each other, and a gap a is maintained between the proximal end side end surface 11 of the moving element 9 and the fixed core side facing surface 3a. I'm leaning. Further, a gap having a distance including the gap a and the gap c is maintained between the armature-side first facing surface 5a and the fixed core-side facing surface 3a. This state is used as a reference position for explaining the movement status of each part thereafter. Therefore, in the portion (1) in FIG. 6, the positions of the mover 9 and the armature 5 are both “0”.

  Next, in the state (2) in FIG. 5, an initial energization state in which the coil 6 is energized is shown. In this state, energization of the coil 6 is started, so that a magnetic field is generated, and a force attracted to the fixed core 3 side is applied to both the armature 5 and the mover 9 made of a magnetic material. However, the armature 5 is pressed to the tip side by the spring 7. Therefore, at this time, the armature 5 cannot move due to a response delay, only the moving element 9 moves to the fixed core 3 side by the gap b, and the shoulder 9b is locked to the locking portion 8a. Yes. As a result, the distal end side end surface 10 of the moving element 9 and the armature side second facing surface 5b are separated by a distance b. Accordingly, in the portion (2) in FIG. 6, the position of the moving element 9 indicates “b”, and the position of the armature 5 still indicates “0”. In addition, the space | interval of the base end side end surface 11 of the needle | mover 9 at this time and the fixed core side opposing surface 3a will be "ab".

  Next, in the state of (3) in FIG. 5, the shoulder 9b of the movable element 9 shown in (2) is engaged with the engaging part 8a, and the movable element 9 and the armature 5 are integrally fixed. It is in a state of being drawn toward the core 3 side. That is, the armature 5 also starts to move toward the fixed core 3 against the elasticity of the spring 7. In this way, the movable element 9 that is pulled together with the armature 5 toward the fixed core 3 is in a state in which the base end side end surface 11 is in contact with the fixed core side facing surface 3a. Here, the tip end side end face 10 of the moving element 9 and the armature side second facing face 5b are still kept separated by a distance b. Accordingly, in the portion (3) in FIG. 6, the position of the movable element 9 is “a”, that is, the position is moved by the gap a in the initial state shown in (1), and the armature 5 is “ab”. That is, it moves by the distance between the base end side end surface 11 of the moving element 9 and the fixed core side facing surface 3a in the state shown in (2).

  Next, in the state of (4) in FIG. 5, the base end side end surface 11 of the moving element 9 is already in contact with the fixed core side facing surface 3a in the state shown in (3). No more moving. On the other hand, since the armature 5 is in the state shown in (3), the tip end surface 10 of the moving element 9 and the armature-side second facing surface 5b are separated by a distance b, and therefore fixed by the distance b. It moves to the core 3 side, and the distal end side end face 10 of the mover 9 and the armature side second facing face 5b are in close contact with each other. Accordingly, in the portion (4) in FIG. 6, the position of the movable element 9 indicates “a” similarly to the portion (3), and the position of the armature 5 also indicates “a”. That is, the movement amount of the armature 5 from the initial position (reference position) is equal to the gap a. Therefore, in the state of (4) in FIG. 5, a gap c equivalent to the gap c is formed between the fixed core side facing surface 3a and the armature side first facing surface 5a, and the two are in close contact with each other. Absent. This state is a state when the needle valve 4 is opened.

  In the state of (4) in FIG. 5, the positional relationship between the armature 5 and the mover 9 is the relationship described above. At this time, the distal end side end surface 10 of the mover 9 and the armature side second facing surface 5b A squeeze effect can be obtained in between. As a result, valve opening bounce of the needle valve 4 is suppressed.

  Next, the operation of each part when the state (4) in FIG. 5, that is, the state when the needle valve 4 is opened to the state when the valve is closed will be described. When the energization of the coil 6 is stopped, the magnetic field disappears, so that the armature 5 biased by the spring 7 and the needle valve 4 integrated therewith start a valve closing operation. At this time, the gap c is formed between the fixed core side facing surface 3a and the armature side first facing surface 5a as described above, and the two are not in close contact with each other. The squeeze effect does not occur. For this reason, the needle valve 4 can start the valve closing operation with good response and can return to the state (1) in FIG.

  In addition, in the state of (4) in FIG. 5, since the base end side end surface 11 of the moving element 9 and the fixed core side facing surface 3a are in close contact with each other, it is considered that a reverse squeeze effect is generated at that location. Since the area of the close contact portion is small, it is considered that the valve closing operation of the needle valve 4 is not so much affected. In addition, the tip end surface 10 of the moving element 9 and the armature-side second facing surface 5b are also in close contact with each other, and it is considered that a reverse squeeze effect is produced at the location, but the moving element 9 itself is fixed. Therefore, it is considered that the reverse squeeze effect at the location does not have a great influence on the valve closing operation of the needle valve 4.

  The valve behavior of the needle valve 4 of the fuel injection device 1 as described above will be described in comparison with a conventional example with reference to FIG. In FIG. 7, reference numerals (1) to (4) indicate times corresponding to the states shown in (1) to (4) shown in FIG. In FIG. 7, Conventional Example 1 indicated by a two-dot chain line shows the valve behavior of the needle valve in the fuel injection device in which the contact area between the fixed core and the armature is increased. When the contact area between the fixed core and the armature is large, the bounce of the valve is not seen in the vicinity of the valve opening shown in (3). On the other hand, the valve response after the coil drive signal is turned off. Is bad. On the other hand, Conventional Example 2 shown by the one-dot chain line in FIG. 7 shows the valve behavior of the needle valve in the fuel injection device in which the contact area between the fixed core and the armature is reduced. When the contact area between the fixed core and the armature is small, the valve response after the coil drive signal is turned off is good, but valve bounce is observed in the vicinity of the valve opening time shown in (3). In contrast to these conventional examples, the valve behavior of the fuel injection device 1 of the present invention indicated by the solid line in FIG. 7 is that no valve bounce is observed near the valve opening time indicated by (3). The valve responsiveness after the coil drive signal is turned off is also good. That is, according to the fuel injection device 1 of the present invention, it was confirmed that suppression of the valve opening bounce and good valve closing response were ensured.

The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope. For example, as shown in FIG. 8, a hole 5c is formed in the armature 5, or a vertical groove 9c is provided in the movable element 9 as shown in FIG. It can be configured. In the fuel injection device 1 of the present invention, the squeeze effect that is generated between the distal end side end surface 10 of the moving element 9 and the armature side second facing surface 5b that is the bottom surface of the recess 8 is utilized. In order to use, it is necessary that the fuel exists in the recess 8. In the above embodiment, the fuel in the valve body 2 can enter the recess 8 from between the locking portion 8a and the small-diameter cylindrical portion 9a, whereby the fuel exists in the recess 8. For this reason, the squeeze effect can be obtained even with the configuration of the above embodiment, but if the hole 5c and the longitudinal groove 9c are provided to communicate the inside and outside of the recess 8, the fuel surely enters the recess 8 and reliably A squeeze effect can be obtained.
Moreover, it can also be set as the structure which does not provide the latching | locking part 8a.

It is the schematic diagram which showed the principal part of the fuel-injection apparatus of this invention. FIG. 2 is an enlarged cross-sectional view of a peripheral portion of a fixed core and an armature of the fuel injection device shown in FIG. 1. It is an expanded sectional view of the base end part of an armature. It is an expanded sectional view of a mover. It is explanatory drawing which shows sequentially the operation | movement of each part at the time of valve opening. It is a graph which shows the movement condition of a mover and an armature. It is a graph which shows the valve behavior of a needle valve. It is an expanded sectional view of the base end part of the armature which provided the hole. It is explanatory drawing of the needle | mover provided with the vertical groove, (a) is a top view, (b) is a front view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection apparatus 2 Valve body 2a Injection hole 3 Fixed core 3a Fixed core side opposing surface 4 Needle valve 5 Armature 5a Armature side first opposing surface 5b Armature side second opposing surface 5c Hole 6 Coil 7 Spring 8 Recess 8a Locking part DESCRIPTION OF SYMBOLS 9 Mover 9a Small diameter cylindrical part 9b Shoulder part 9c Vertical groove 10 Front end side end face 11 Base end side end face

Claims (4)

A valve body in which an injection hole is formed;
A fixed core mounted in the valve body;
An armature that is housed in a reciprocating manner closer to the tip side than the fixed core in the valve body, and includes a needle valve that opens and closes the injection hole on the tip side;
A coil that causes the armature to approach and separate from the fixed core according to the energized state;
In a fuel injection device having an armature pressing means for pressing the armature so that the needle valve is in a closed state,
The front end side end surface of the fixed core is a fixed core side facing surface,
The armature is formed with an armature-side first facing surface that faces the fixed core-side facing surface, and an armature-side second facing surface that is located on the tip side of the armature-side first facing surface,
Provided with a mover made of a magnetic material that reciprocates separately from the armature between the armature-side second facing surface and the fixed core-side facing surface,
The fixed core side facing surface and the armature side first facing surface in a state where the distal end side end surface of the moving element is in close contact with the armature side second facing surface and the proximal end surface is in close contact with the fixed core side facing surface. A fuel injection device characterized in that a gap is formed between the two. The fuel injection device according to claim 1, wherein
A fuel injection device, wherein a recess is provided on the base end side of the armature, and the bottom surface of the recess is the armature-side second facing surface. The fuel injection device according to claim 2, wherein
While forming a small diameter cylindrical portion and a shoulder portion continuous to the small diameter cylindrical portion on the proximal end side of the moving element,
The fuel injection device according to claim 1, wherein a locking portion for locking the shoulder portion is formed at an opening end portion of the concave portion. The fuel injection device according to claim 2 or 3,
A fuel injection device characterized in that a passage for communicating the inside and outside of the recess is formed in the armature and / or the moving element.

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