JP2017082693A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device capable of securing sufficient waterproof performance with an inner periphery mold structure.SOLUTION: A fuel injection device includes a fixed core 107, a movable core 106, a coil 108 generating magnetic attraction force between the fixed core 107 and the movable core 106 by being energized, a housing 109 positioned in an outer peripheral side of the coil 108 and storing the coil 108, and a resin 117 filled in an inner peripheral side of the housing 109 and covering the coil 108. The housing 109 has a plane portion 109a in a direction crossing a center axis line direction, and a surface of the plane portion 109a is roughed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel injection device for injecting fuel into an internal combustion engine, particularly an automobile engine.

  A fuel injection device (fuel injection valve) is mounted on an internal combustion engine and is exposed to a severe environment such as water exposure and a temperature cycle. In particular, when water enters the coil portion of the fuel injection device, an electrical conduction path is formed between the inner peripheral surface of the housing and the coil, and the insulation resistance of the coil is reduced. There is a risk. For this reason, it is necessary to improve the waterproof performance of a coil part.

  As a background art of this technical field, there is a fuel injection valve described in JP 2010-203411 A (Patent Document 1). The fuel injection valve is formed with a fuel passage and an injection hole, and a body that houses a needle that opens and closes the injection hole, a coil that generates a magnetic field when current is supplied, and a needle that moves in the opening and closing direction. And a fixed core that generates a magnetic attractive force that attracts the movable core, a housing that covers the outside of the coil, and a connector that has a terminal that supplies current to the coil. The connector has an insulating portion that covers the terminal and a supporting portion that supports the insulating portion, and the supporting portion is accommodated in a recess formed at the end of the housing and supported by the outer peripheral wall of the body and the inner peripheral wall of the housing. (See summary).

  In this fuel injection valve, the insulating portion and the support portion are made of resin (see paragraph 0089). A groove extending in the circumferential direction is formed on the inner peripheral wall of the housing, and the axial contact length between the support portion made of resin and the inner peripheral wall of the housing is increased. As a result, the fuel injection valve suppresses the entry of moisture and the like into the coil accommodated on the inner peripheral side of the housing (see paragraph 0123).

JP 2010-203411 A

  In the fuel injection valve of Patent Document 1, a coil is housed in a housing chamber formed on the inner peripheral side of the housing, and waterproofing is ensured by filling the housing chamber with resin. Further, in this fuel injection valve, the circumferentially extending groove formed in the inner peripheral wall of the housing increases the axial contact length between the resin portion (supporting portion) and the housing inner peripheral wall, thereby improving waterproofness. Yes.

  However, the structure of this fuel injection valve is a structure in which the housing is filled with resin (inner peripheral mold structure), and a gap is generated at the interface between the housing and the resin due to shrinkage after resin molding, and the coil is formed from this gap. There is a risk of water entering the containment chamber. In this fuel injection valve, the circumferential groove formed on the inner peripheral wall of the housing increases the axial contact length between the resin portion and the inner peripheral wall of the housing, thereby improving the waterproof property. In order to improve waterproofness in consideration, it is necessary to increase the number of rows of the groove portions, and it is necessary to lengthen the formation region of the groove portions in the axial direction. For this reason, in order to ensure sufficient waterproof performance, a fuel injection valve may enlarge in an axial direction.

  In addition, it is possible to improve the waterproof performance by molding the resin portion on the outer peripheral surface of the housing (peripheral mold structure), but in the outer peripheral mold structure, it is necessary to cover the upper end surface of the housing with resin. However, in the structure for attaching the fuel injection valve to the engine, the upper end surface of the housing is pressed and fixed to the engine, so that it is difficult to obtain an outer peripheral mold structure.

  Further, in this fuel injection valve, the resin enters the groove portion formed in the inner peripheral wall of the housing, and the resin adheres to the housing surface by the anchor effect, so that waterproofness can be ensured. However, depending on the shrinking direction after resin molding, the resin may come off from the groove formed in the inner peripheral wall of the housing, and a gap may be formed at the interface between the resin and the metal. In Patent Document 1, consideration for this is not sufficient.

  The objective of this invention is providing the fuel-injection apparatus which can ensure sufficient waterproof performance with an inner periphery mold structure.

  In order to solve the above problems, the fuel injection device of the present invention has a shape of a housing inner peripheral surface having a flat portion in a direction intersecting the central axis direction, and the surface of the flat portion is roughened with a resin. It was set as the structure filled.

  According to the present invention, since the flat portion is roughened, the resin is prevented from shrinking in a direction parallel to the plane of the flat portion, and the waterproof performance is ensured by maintaining the contact between the resin and the flat portion. can do.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is sectional drawing which shows the whole structure about one Example of the fuel-injection apparatus which concerns on this invention. It is an enlarged view which shows the 1st Example of the coil accommodating part which concerns on this invention. It is an enlarged view which shows the 2nd Example of the coil accommodating part which concerns on this invention. It is an enlarged view which shows the 3rd Example of the coil accommodating part which concerns on this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The fuel injection device of this embodiment is suitable for use in an internal combustion engine, particularly an automobile engine using gasoline as fuel.

  An overall configuration of an embodiment of the fuel injection device 100 according to the present invention will be described with reference to FIG. FIG. 1 is a sectional view showing the overall structure of an embodiment of a fuel injection device according to the present invention. In the following, all the drawings are exaggerated for the purpose of explanation, and are different from actual dimensions.

  The fuel injection device 100 of the present embodiment drives the valve body 101 with electromagnetic force, and is also called an electromagnetic fuel injection valve (electromagnetic injector).

  In the following description, the vertical direction is defined and described with reference to FIG. This vertical direction has nothing to do with the vertical direction when the fuel injection device 100 is mounted on the engine. In some cases, the end on the fuel supply port 115 side of the fuel injection device 100 is referred to as a proximal end, and the end opposite to the proximal end is referred to as a distal end.

  The upper portion (fuel supply port) 115 of the fixed core 107 in FIG. 1 is provided with a high-pressure pump (not shown) for supplying fuel under pressure, and a pipe connecting the high-pressure pump and the fuel supply port 115. The fuel is supplied in a pressurized state from the fuel supply port 115 to a through hole 112 that is formed in the center portion of the fixed core 107 and forms a fuel passage. The through hole 112 and the fuel passage constituted by the through hole 112 are extended in a direction along the central axis 100 a of the fuel injection device 100.

  A movable core 106 is provided at the upper end of the valve body 101, and a seating surface for the spring 110 is provided on the movable core 106. In this embodiment, the movable core 106 is fixed to the valve body 101. However, the movable core 106 may be configured to be relatively displaceable with respect to the valve body 101 in a direction along the central axis 100a. The valve body 101 is disposed such that its axis (axial direction) is along the central axis 100a.

  The upper end of the spring 110 opposite to the valve body 101 is in contact with the lower end of the adjuster 111. The adjuster 111 is fixed to the inner peripheral surface of the through hole 112 of the fixed core 107. As a result, the spring 110 has one end (upper end) in contact with the adjuster 111 and the other end (lower end) in contact with the movable core 106. The spring 110 is assembled in a compressed state between the adjuster 111 and the movable core 106, and is urged with respect to the movable core 106 in the valve closing direction (direction in contact with the fixed valve 102).

  The valve body 101 is held by a guide member 103 and a mover guide 105 so as to reciprocate in the vertical direction (open / close valve direction). During the valve closing period (valve closed state) in which the coil 108 is not energized, the valve body 101 is in contact with the fixed valve 102 provided at the tip of the nozzle 104 by the urging force of the spring 110, and from the high pressure pump. The flow of supplied fuel is cut off.

  In the present embodiment, the part of the fixed valve 102 with which the valve body 101 abuts is particularly called a valve seat 102a. The valve seat 102a is provided on a valve seat surface formed on the inner surface of the nozzle 104 (nozzle member). The valve seat surface is formed in a conical surface shape whose diameter decreases from the upstream side toward the downstream side. A portion where the valve seat surface and the valve body 101 abut is called a seat portion, and in this embodiment, the seat portion on the valve seat surface side is called a valve seat 102a. An injection hole 12 b is formed on the downstream side of the valve seat 102 a of the nozzle 104. There may be one or more injection holes 12b.

  The valve seat 102a and the valve body 101 cooperate to open and close the fuel passage, inject fuel by opening the fuel passage, and stop fuel injection by closing the fuel passage. By opening the fuel passage between the valve seat 102a and the valve body 101, the fuel that has passed through the seat portion between the valve seat 102a and the valve body 101 is injected to the outside from the injection hole 102b.

  A portion connecting the seat portion of the valve body 101 and the movable core 106 is formed in a rod shape and may be referred to as a rod portion. Further, the valve body 101 and the movable core 106 constitute a mover for opening and closing the valve portion.

  The fixed core 107 is fixed to the inner peripheral side of the cylindrical portion 104 a of the nozzle 104. A movable core 106 is accommodated on the inner peripheral side of the cylindrical portion 104 a of the nozzle 104, and the upper end surface of the movable core 106 faces the lower end surface of the fixed core 107. In the closed state, a magnetic gap δ1 is provided between the upper end surface of the movable core 106 and the lower end surface of the fixed core 107. The movable core 106 is disposed at a position where the outer peripheral surface thereof faces the lower end portion of the housing 109 via the cylindrical portion 104a.

  The coil 108 is disposed on the outer peripheral portion of the fixed core 107, and a toroidal magnetic path indicated by an arrow 122 is formed through the movable core 106 that is integral with the housing 109, the tubular portion 104a of the nozzle 104, and the valve body 101. Is formed. The housing 109 constitutes an electromagnet yoke composed of the coil 108 and the fixed core 107.

  In addition, a plug for supplying power from a battery (not shown) is connected to the connector 114 formed at the tip of the terminal 113. The coil 108 is controlled between an energized state and a non-energized state by a controller (not shown). The coil 108 is supplied with current through the end 113a of the terminal 113 when energized.

While the coil 108 is energized, a magnetic attractive force is generated between the movable core 106 and the fixed core 107 by the magnetic flux passing through the magnetic path 122. The movable core 106 moves upward by being sucked by the fixed core 107 and moves until it collides with the lower end surface of the fixed core 107. In other words, the movable core 106 moves a distance (stroke) corresponding to the magnetic gap δ 1. As a result, the valve body 101 is opened away from the valve seat 102 a of the fixed valve 102, and the fuel passage in the center of the fixed core 107. The fuel supplied from the through hole 112 is injected into the combustion chamber from the injection hole 102b.

  When the power supply to the coil 108 is cut off, the magnetic flux in the magnetic path 122 disappears and the magnetic attractive force disappears. In this state, the spring force of the spring 110 that urges the valve body 101 in the valve closing direction acts on the valve body 101. As a result, the valve body 101 is pushed back to the valve closing position in contact with the fixed valve 102.

  Here, the features of the first embodiment will be described with reference to FIG. FIG. 2 is an enlarged view showing a first embodiment of the coil housing portion according to the present invention.

  The coil 108 is housed in a coil housing portion (coil housing chamber) 116. The coil housing portion 116 is provided on the inner peripheral side of the housing 109. Moreover, the coil accommodating part 116 is arrange | positioned on the outer peripheral side of the cylindrical part 104a of the fixed core 107 and the nozzle 104, and the downward direction of the flange part 107a. That is, the coil housing portion 116 is formed by a cylindrical housing 109, a cylindrical nozzle 104 that is fixed by being press-fitted and welded to the inner peripheral side of the cylindrical housing 109, and a flange portion 107 a of the fixed core 107. The The remaining space in the coil housing portion 116 after housing the coil 108 is filled with a resin that forms the connector 114.

  The flange portion 107 a is provided so as to protrude from the outer peripheral surface of the fixed core 107 toward the inner peripheral surface of the housing 109. The flange portion 107 a forms a magnetic path between the cylindrical portion of the fixed core 107 and the housing (yoke) 109.

  The housing 109 is formed with a flat portion 109a on the entire inner peripheral surface in a direction intersecting the fuel flow path (the direction of the central axis 100a and the axial direction of the valve body 101) and facing the upstream direction of the fuel flow path. In the present embodiment, an inner peripheral surface 109c having a large diameter is formed at the upper end portion of the housing 109, an inner peripheral surface 109d having a smaller diameter than the inner peripheral surface 109c is formed on the lower side (tip side) thereof, and the inner peripheral surface 109c is formed. And the inner peripheral surface 109d form a flat surface portion 109a. That is, an inner peripheral surface 109c having a diameter larger than that of the inner peripheral surface 109d is formed on the base end side (upper end side of the housing 109) of the inner peripheral surface 109d, and the step surface between the inner peripheral surface 109c and the inner peripheral surface 109d is flat. Part 109a is configured.

  A portion of the housing 109 that accommodates the coil 108 is formed in a cylindrical shape, and the central axis of the cylindrical portion coincides with the central axis 100 a of the fuel injection device 100. Accordingly, the flat portion 109 a is formed so as to intersect the central axis of the housing 109.

  The surface of the flat portion 109a is roughened by laser, chemical etching, or the like, and the resin enters the irregularities on the roughened surface of the flat portion 109a when filling the resin.

  The flat portion 109a is preferably perpendicular to the fuel flow path (the direction of the central axis 100a and the axial direction of the valve body 101).

  Thereby, the anchor effect by the unevenness | corrugation of the rough surface of the plane part 109a is acquired, and the resin 117 adheres to the surface (inner peripheral surface) 109c, 109d of the housing 109, and waterproofing can be ensured. That is, after the resin molding, the resin 117 is prevented from contracting in the direction away from the housing inner peripheral surfaces 109c and 109d in the radial direction (the direction parallel to the plane of the flat portion 109a). The separation from 109d can be suppressed. Further, it is possible to ensure the waterproof performance by maintaining the contact between the resin 117 and the flat portion 109a.

  The flat portion 109a may be formed on the inner peripheral surface of the housing, but the distance between the outer peripheral surface of the coil 108 and the inner peripheral surface of the housing 109 is very narrow. Therefore, if the flat portion 109a is provided at a position overlapping the coil 108 in the direction of the central axis 100a, a state in which the resin is not filled around the flat portion 109a may occur. In that case, the anchor effect of the roughened surface of the flat surface 109a described above cannot be obtained.

  Further, as described above, the distance between the outer peripheral surface of the coil 108 and the inner peripheral surface of the housing 109 is very narrow. For this reason, it may be difficult to increase the size of the flat portion 109a in the radial direction of the housing 109, and it may be difficult to obtain a large anchor effect.

  When the anchor effect of the roughened surface of the flat portion 109a cannot be obtained, a gap is formed between the housing 109 and the resin 117, and water that has entered the gap may reach the coil 108 and come into contact with the coil 108. is there. Therefore, it is desirable that the flat portion 109a is located between the end surface 109b of the housing 109 and the coil upper end surface 108a.

  A flange portion 107 a of the fixed core 107 is provided on the upper side of the upper end of the coil 108. For this reason, the space | interval of the outer peripheral surface of the flange part 107a and the inner peripheral surface of the housing 109 also becomes very narrow. Therefore, it is more desirable that the flat portion 109a is located between the end surface 109b of the housing 109 and the upper end surface 107aa of the flange portion 107a. However, since the flange portion 107 a is provided in the vicinity of the upper end portion 109 b of the housing 109, the resin flows more easily than in the vicinity of the outer peripheral surface of the coil 108. For this reason, even if the flat portion 109a is provided on the inner peripheral surface portion of the housing 109 facing the outer peripheral surface of the flange portion 107a, the resin easily flows into the flat portion 109a.

  The shrinkage direction of the resin 117 after molding shrinks not only in the direction along the central axis 100a of the fuel injection device 100 but also in the direction perpendicular to the central axis 100a (the radial direction of the housing 109). For this reason, if the inner peripheral surface 109b of the housing 109 is only roughened without providing the flat portion 109a, the resin 117 that has entered the irregularities on the roughened surface escapes from the irregularities on the roughened surface due to shrinkage after resin molding. There is a risk. If the resin 117 comes out of the irregularities on the roughened surface, a gap is formed at the interface between the inner peripheral surface 109b of the housing 109 and the resin 117, and it is difficult to prevent water from entering the coil 108.

  According to the above-described configuration, it is possible to suppress the resin 117 that has entered the unevenness of the flat portion 109a from shrinking in the removal direction from the unevenness even with respect to the shrinkage after the resin molding. Thereby, separation of the resin 117 and the inner peripheral surface 109b of the housing 109 can be prevented by the anchor effect of the resin 117, and waterproof performance can be ensured.

  Furthermore, since the waterproof performance can be improved if the area of the flat portion 109a is increased, it is desirable that the inner diameter of the flat portion 109a be a minimum dimension that allows the coil 108 to be assembled.

  In the present embodiment, the flat portion 109a may be configured at the same height position as the upper end surface 109b of the housing 109, that is, in the same plane as the upper end surface 109b, and the resin 117 may be molded on the portion of the flat portion 109a. . In this case, although the flat portion 109a is covered with the resin 117, the upper end surface 109b of the housing 109 that is not covered with the resin 117 exists on the outer peripheral side of the flat portion 109a. Can be fixed to.

  Next, a second embodiment will be described with reference to FIG. FIG. 3 is an enlarged view showing a second embodiment of the coil housing portion according to the present invention.

  Compared to the first embodiment, the second embodiment has a configuration in which the inner diameter of the upper end portion 109b of the housing is set to the minimum dimension capable of assembling the coil 108, and the flat portion 109a is provided on the entire inner peripheral surface of the housing 109. It is. At this time, the flat portion 109a is configured as a surface facing the downstream direction of the fuel flow path (the tip side of the fuel injection device 100).

  The point that the flat portion 109a is formed in a direction intersecting with the fuel flow path (the direction of the central axis 100a and the axial direction of the valve body 101) is the same as in the first embodiment. Further, as in the first embodiment, the plane portion 109a is preferably perpendicular to the fuel flow path (the direction of the central axis 100a and the axial direction of the valve body 101).

  In this embodiment, the inner diameter of the inner peripheral surface 109c of the housing upper end portion 109b is smaller than the inner diameter of the inner peripheral surface 109d of the housing 109 at the outer peripheral portion of the coil 108. Therefore, the flat portion 109a configured as a stepped surface between the inner peripheral surface 109c and the inner peripheral surface 109d is configured as a surface facing the lower end side (tip end side) of the fuel injection device 100.

  In this configuration, since the flat surface portion 109a is configured as a surface facing the lower end side of the fuel injection device 100, when a laser is used as a method for roughening the surface of the flat surface portion 109a, roughening work is performed as compared with the first embodiment. Becomes difficult. However, if the chemical etching process is employed, the flat portion 109a can be easily roughened by roughening the entire surface of the housing 109. For this reason, the waterproof performance similar to 1st Example is securable.

  In this configuration, since the flat portion 109 a is configured as a surface facing the lower end side of the fuel injection device 100, it is formed between the outer peripheral surface of the coil 108 and the outer peripheral surface of the flange portion 107 a and the inner peripheral surface 109 d of the housing 109. The gap is wider than in the first embodiment. For this reason, filling of the resin 117 becomes easy.

  However, due to restrictions on the outer diameter of the fuel injection device 100, there is a limit to increasing the gap formed between the outer peripheral surface of the coil 108 and the outer peripheral surface of the flange portion 107a and the inner peripheral surface 109d of the housing 109. is there. Therefore, it is desirable that the flat portion 109a is located between the end surface 109b of the housing 109 and the coil upper end surface 108a. Further, it is more desirable that the flat portion 109a is located between the end surface 109b of the housing 109 and the upper end surface 107aa of the flange portion 107a.

  Further, the flat surface portion 109 a can be roughened by irradiating the inner peripheral surface of the housing 109 with a laser from the opening portion into which the cylindrical portion 104 a of the nozzle 104 is inserted.

  Except for the configuration described above, the second embodiment is the same as the first embodiment, and an anchor effect similar to that of the first embodiment can be obtained as the anchor effect of the flat portion 109a.

  Next, a third embodiment will be described with reference to FIG. FIG. 4 is an enlarged view showing a third embodiment of the coil housing portion according to the present invention.

  In the second embodiment, a rectangular portion 109e is provided on the entire circumference of the inner peripheral surface below the upper end portion (base end side end portion) 109b of the housing 109, so that the flat portion 109a is directed in the direction of the fuel flow path. A plurality are provided to roughen the surface.

  The point that the flat portion 109a is formed in a direction intersecting with the fuel flow path (the direction of the central axis 100a and the axial direction of the valve body 101) is the same as in the first embodiment. Further, as in the first embodiment, the plane portion 109a is preferably perpendicular to the fuel flow path (the direction of the central axis 100a and the axial direction of the valve body 101).

  In this embodiment, by providing one rectangular portion 109e, two flat portions 109a can be provided on the upper surface and the lower surface of the rectangular portion 109e. By providing a plurality of rectangular portions 109e, more plane portions 109a can be provided.

  According to this configuration, since a large area of the flat portion 109a can be secured, it is possible to more surely prevent the resin from being removed from the unevenness formed on the surface of the flat portion 109a even against shrinkage after resin molding. it can.

  Furthermore, the path length to the coil 108 can be secured against water intrusion from the interface between the housing 109 and the resin 117, and a more reliable waterproof structure can be obtained.

  In the first to third embodiments, the end surface portion 109b of the housing 109 is not covered with resin, and the surface is exposed. Thereby, when attaching a fuel-injection apparatus to an engine, the housing end surface part 109b can be pressed and fixed.

  Also in this embodiment, as in the first embodiment, the flat portion 109a is preferably located between the end surface 109b of the housing 109 and the coil upper end surface 108a.

  Except for the configuration described above, the second embodiment is the same as the first embodiment, and an anchor effect similar to that of the first embodiment can be obtained as the anchor effect of the flat portion 109a.

  In order to exhibit the anchor effect, the flat surface portion 109a described in the first embodiment to the third embodiment is rough so that the depth dimension of the unevenness is larger than the distance between the tops of the adjacent protrusions. It has become. For example, when the flat surface portion 109a is roughened by a laser, the surface roughness of the flat surface portion 109a is greater than the average surface roughness of the inner peripheral surface of the housing 109 or the surface roughness of the inner surface of the housing 109 other than the flat surface portion 109a. large.

  In addition, this invention is not limited to each above-mentioned Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  DESCRIPTION OF SYMBOLS 101 ... Valve body, 102 ... Fixed valve, 103 ... Guide member, 104 ... Nozzle, 105 ... Movable element guide, 106 ... Movable core, 107 ... Fixed core, 108 ... Coil, 108a ... Upper end part of coil, 109 ... Housing, 109a DESCRIPTION OF SYMBOLS ... Housing flat surface part 109b ... Housing end surface part, 109e ... Rectangular shape part, 110 ... Spring, 111 ... Adjuster, 112 ... Through-hole, 113 ... Terminal end part, 114 ... Connector, 116 ... Coil accommodating part (coil accommodating chamber) 117) Resin.

Claims (5)

A fixed core, a movable core, a coil that generates a magnetic attractive force between the fixed core and the movable core when energized, and a housing that is located on the outer peripheral side of the coil and accommodates the coil; A fuel injection device comprising: a resin that fills the inner peripheral side of the housing and covers the coil;
The housing has a plane portion in a direction intersecting the central axis direction,
The flat surface portion has a roughened surface. The fuel injection device according to claim 1,
The fuel injection device according to claim 1, wherein the flat portion is formed on the entire inner peripheral surface of the housing. The fuel injection device according to claim 2, wherein
The fuel injection device according to claim 1, wherein the flat portion is located between an upper end portion of the housing and an upper end portion of the coil. The fuel injection device according to claim 3, wherein
The housing has a rectangular portion on the inner peripheral surface,
A plurality of the planar portions are constituted by an upper surface and a lower surface of the rectangular portion, and the fuel injection device is characterized in that The fuel injection device according to claim 4, wherein
The fuel injection device according to claim 1, wherein a surface of an upper end portion of the housing is exposed from the resin.

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